Should I voe an egg to the hatch of it's clutch than the via is of the Turtle at it's bae'd,
of that is the batch of Hutch in the cabinet of that massive rock to sled,
in the fossil is the direct on the Ages of the Times.??
To nigh the hour with the vegetable on the garden is to upped of the value on measuring,
an inch to the foot of yard,
an ankle to the knee of galaxy,
at the Universe is the Sun of the moon on it's chest to Sea!!
Upper on the jaw is the teeth of what is a gum,
as the calcium yanks to that it's the gears?,
what is the mechanic of the car burr rate door?
Engine and Bellows,
chimney's as the fire in the would of Cosmic eye!!
Adder stone
An adder stone is a type of stone, usually glassy, with a naturally occurring hole through it. Such stones have been discovered by archaeologists in both Britain and Egypt. Commonly, they are found in Northern Germany at the coasts of the North and Baltic Seas.
In Britain they are also called hag stones,[1] witch stones, serpent's eggs, snake's eggs, or Glain Neidr in Wales, milpreve in Cornwall, adderstanes in the south of Scotland and Gloine nan Druidh ("Druids' glass" in Scottish Gaelic) in the north. In Egypt they are called aggryor aggri.
Adder stones were believed to have magical powers such as protection against eye diseases or evil charms, preventing nightmares, curing whooping cough, the ability to see through fairy or witch disguises and traps if looked at through the middle of the stone, and recovery from snakebite. According to popular conception, a true adder stone will float in water.
Three traditions exist as to the origins of adder stones. One holds that the stones are the hardened saliva of large numbers of serpentsmassing together, the perforations being caused by their tongues. The second claims that an adder stone comes from the head of a serpent or is made by the sting of an adder. The third is more modern (and much easier to attain). It details that the stone can be any rock with a hole bored through the middle by water. Human intervention (i.e., direction of water or placement of the stone) is not allowed.[2]
Contents
[hide]The Druids[edit]
Adder stone was held in high esteem amongst the Druids. It was one of their distinguishing badges, and was accounted to possess the most extraordinary virtues. There is a passage in Pliny’s Natural History, book XXII, describing the nature and the properties of this amulet. The following is a translation of it:
- "There is a sort of egg in great repute among the Gauls, of which the Greek writers have made no mention. A vast number of serpents are twisted together in summer, and coiled up in an artificial knot by their saliva and slime; and this is called "the serpent's egg". The druids say that it is tossed in the air with hissings and must be caught in a cloak before it touches the earth. The person who thus intercepts it, flies on horseback; for the serpents will pursue him until prevented by intervening water. This egg, though bound in gold will swim against the stream. And the magi are cunning to conceal their frauds, they give out that this egg must be obtained at a certain age of the moon. I have seen that egg as large and as round as a common sized apple, in a chequered cartilaginous cover, and worn by the Druids. It is wonderfully extolled for gaining lawsuits, and access to kings. It is a badge which is worn with such ostentation, that I knew a Roman knight, a Vocontian, who was slain by the stupid emperor Claudius, merely because he wore it in his breast when a lawsuit was pending."[3]
Huddleston's edition of John Toland's "History of the Druids" gives some very ingenious conjectures on the subject of this very enigmatical Druids' egg. The amulets of glass and stone, which are still preserved and used with implicit faith in many parts of Scottish Gaeldom, and are conveyed, for the cure of diseases to a great distance, seem to have their origin in this bauble of ancient priestcraft.[4]
In Welsh mythology[edit]
The Glain Neidr or Maen Magi of Welsh folklore is also closely connected to Druidism. The Glain Neidr of Wales are believed to be created by a congress of snakes, normally occurring in spring, but most auspicious on May Eve.[5]
Although not named as Glain Neidr, magic stones with the properties of adder stones appear frequently in Welsh mythology and folklore. The Mabinogion, translated into English in the mid-nineteenth century by Lady Charlotte Guest, mentions such stones on two occasions. In the story of Peredur son of Efrawg (Percival of the Arthurian cycle), in a departure from Chrétien de Troyes' Perceval, the Story of the Grail, Peredur is given a magical stone that allows him to see and kill an invisible creature called the Addanc.[6] In another tale, Owain, or the Lady of the Fountain (Ywain of Arthurian legend), the hero Owain mab Urien is trapped in the gatehouse of a castle. He is given a stone by a maiden, which turns Owain invisible, allowing him to escape capture.
In Irish mythology[edit]
While serpents, not being present in Ireland don't often feature in Irish mythology other creatures can form parallels. The legendary druid Mug Ruith was said to have a stone which could turn into a poisonous eel when thrown in water, this may be a reference to an Adder Stone.
In Russian Mythology[edit]
In Russian folklore, adder stones were believed to be the abodes of spirits called Kurinyi Bog ("The Chicken God"). Kurinyi Bog were the guardians of chickens, and their stones were placed into farmyards to counteract the possible evil affects of the Kikimora (The wives of the Domovoi, the house spirits.) Kikimora, who also guarded and took care of chickens, could often unleash misery upon hens they did not like by plucking out their feathers.[7]
Sea turtle
| Sea turtles Temporal range: Early Cretaceous-Holocene,[1] 110–0 Ma | |
|---|---|
 | |
| An olive ridley sea turtle, a species of the sea turtle superfamily | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Testudines |
| Suborder: | Cryptodira |
| Clade: | Americhelydia |
| Clade: | Panchelonioidea |
| Superfamily: | Chelonioidea Bauer, 1893[2] |
| Type species | |
| Chelonia mydas Linnaeus, 1758 | |
| Families | |
| Synonyms[2] | |
Chelonii - Oppel 1811
Chlonopteria - Rafinesque 1814 Cheloniae - Schmid 1819 Edigitata - Haworth 1825 Oiacopodae - Wagler 1828 Pterodactyli - Mayer 1849 | |
Sea turtles (superfamily Chelonioidea), sometimes called marine turtles,[3] are reptiles of the order Testudines. The seven extant species of sea turtles are: the green, loggerhead, Kemp's ridley, olive ridley, hawksbill, flatback, and leatherback.[4]
Description[edit]
The majority of a sea turtle's body is protected by its shell. The turtle's shell is divided into two sections: carapace (the dorsal portion) and plastron (the ventral portion). The shell is made up of smaller plates called scutes. The leatherback is the only sea turtle that does not have a hard shell. Instead, it bears a mosaic of bony plates beneath its leathery skin.
In general, sea turtles have a more fusiform body plan than their terrestrial or freshwater counterparts. The reduced volume of a fusiform body means sea turtles can not retract their head, legs, and arms into their shells for protection like other turtles can.[5] However this more stream-line body plan reduces drag in the water and allows the turtle to swim more easily.
The leatherback is the largest species of sea turtle. Measuring 2–3 meters (6–9 ft) in length, and 1-1.5 m (3–5 ft) in width, weighing up to 700 kilograms (1500 lb). Other species are smaller, being mostly 60–120 cm (2–4 ft) and proportionally narrower.[6]
Taxonomy and evolution[edit]
Sea turtles, along with other turtles and tortoises, are part of the order Testudines. All species except the leatherback are in the family Cheloniidae. The leatherback is the only extant member of the family Dermochelyidae.
The origin of sea turtles goes back to the Late Jurassic (150 million years ago) with genera such as Plesiochelys, from Europe. In Africa, the first marine turtle is Angolachelys, from the Turonian of Angola.[7] However, neither of these are related to extant sea turtles; the oldest representative of the lineage leading to these was Desmatochelys padillai , from the Early Cretaceous.
A lineage of unrelated marine testudines, the pleurodire bothremydids, also survived well into the Cenozoic. Other pleurodires are also thought to have lived at sea, such as Araripemys.[8]
Sea turtles constitute a single radiation that became distinct from all other turtles at least 110 million years ago.[9][10][11]
Cladogram[edit]
Below is a cladogram showing the phylogenetic relationships of living and extinct sea turtles in the Chelonioidea based on Peer and Lee (2005)[12]
|
Distribution and habitat[edit]
Sea turtles can be found in oceans except for the polar regions. The flatback sea turtle is found solely on the northern coast of Australia. The Kemp's ridley sea turtle is found solely in the Gulf of Mexico and along the East Coast of the United States.[13]
Sea turtles are generally found in the waters over continental shelves. During the first three to five years of life, sea turtles spend most of their time in the pelagic zone floating in seaweed mats. Green sea turtles in particular are often found in Sargassum mats, in which they find shelter and food.[14] Once the sea turtle has reached adulthood it moves closer to the shore.[15] Females will come ashore to lay their eggs on sandy beaches during the nesting season.[16]
The habitat of a sea turtle has a significant influence on its morphology. Sea turtles are able to grow so large because of the immense size of their habitat: the ocean. The reason that sea turtles are much bigger than land tortoises and freshwater turtles is directly correlated with the vastness of the ocean, and the fact that they travel such far distances, especially the leatherback sea turtles.[17] Having more room to live enables more room for growth.
Life cycle[edit]
It takes decades for sea turtles to reach sexual maturity. Mature turtles may migrate thousands of miles to reach breeding sites. After mating at sea, adult female sea turtles return to land to lay their eggs. Different species of sea turtles exhibit various levels of philopatry. In the extreme case, females return to the beach where they hatched. This can take place every two to four years in maturity.
The mature nesting female hauls herself onto the beach, nearly always at night, and finds suitable sand in which to create a nest. Using her hind flippers, she digs a circular hole 40 to 50 centimetres (16 to 20 in) deep. After the hole is dug, the female then starts filling the nest with her clutch of soft-shelled eggs. Depending on the species, a typical clutch may contain 50–350 eggs. After laying, she re-fills the nest with sand, re-sculpting and smoothing the surface, and then camouflaging the nest with vegetation until it is relatively undetectable visually.[14] The whole process takes thirty to sixty minutes. She then returns to the ocean, leaving the eggs untended.[18]
Females may lay 1–8 clutches in a single season. Female sea turtles alternate between mating in the water and laying their eggs on land. Most sea turtle species nest individually. But ridley sea turtles come ashore en masse, known as an arribada (arrival). With the Kemp's ridley sea turtles this occurs during the day.
Sea turtles have temperature-dependent sex determination, meaning the developing turtle's sex depends on the temperature it is exposed to.[19][20][21][22][23] Warmer temperatures produce female hatchlings, while cooler temperatures produce male hatchlings.[19][20][21][22][23][24] The eggs will incubate for 50–60 days. The eggs in one nest hatch together over a short period of time. The baby turtles break free of the egg shell, dig through the sand, and crawl into the sea. Most species of sea turtles hatch at night. However, the Kemp's ridley commonly hatches during the day. Turtle nests that hatch during the day are more vulnerable to predators, and may encounter more human activity on beach.
Larger hatchlings have a higher probability of survival than smaller individuals, which can be explained by the fact that larger offspring are faster and thus less exposed to predation. Predators can only functionally intake so much; larger individuals are not targeted as often. A study conducted on this topic shows that body size is positively correlated with speed, so larger turtles are exposed to predators for a shorter amount of time.[25] The fact that there is size dependent predation on chelonians has led to the evolutionary development of large body sizes.
In 1987, Carr discovered that the young of green and loggerhead seaturtles spent a great deal of their pelagic lives in floating sargassummats. Within these mats, they found ample shelter and food. In the absence of sargassum, sea turtle young feed in the vicinity of upwelling"fronts".[14] In 2007, Reich determined that green sea turtle hatchlings spend the first three to five years of their lives in pelagic waters. In the open ocean, pre-juveniles of this particular species were found to feed on zooplankton and smaller nekton before they are recruited into inshore seagrass meadows as obligate herbivores.[15][26]
Physiology[edit]
Osmoregulation[edit]
Sea turtles maintain an internal environment that is hypotonic to the ocean. To maintain hypotonicity they must excrete excess salt ions.[27] Like other marine reptiles, sea turtles rely on a specialized gland to rid the body of excess salt ions, because reptilian kidneys cannot produce urine with a higher ion concentration than sea water.[28] All species of sea turtles have a lachrymal gland in the orbital cavity, capable of producing tears with a higher salt concentration than sea water.[29]
Leatherbacks face an increased osmotic challenge compared to other species of sea turtle, since their primary prey are jellyfish and other gelatinous plankton, whose fluids have the same concentration of salts as sea water. The much larger lachrymal gland found in leatherbacks may have evolved to cope with the higher intake of salts from their prey. A constant output of concentrated salty tears may be required to balance the input of salts from regular feeding, even considering leatherback tears can have a salt ion concentration almost twice that of other species of marine turtle.[30]
Hatchlings depend on drinking sea water immediately upon entering the ocean to replenish water lost during the hatching process. Salt gland functioning begins quickly after hatching, so that the young turtles can establish ion and water balance soon after entering the ocean. Survival and physiological performance hinge on immediate and efficient hydration following emergence from the nest.[28]
Thermoregulation[edit]
Most sea turtles (those in family Cheloniidae) are poikilotherms.[31] However the leatherback (family Dermochelyidae) are endothermsbecause they can maintain a body temperature 8 °C (14 °F) warmer than the ambient water.[31]
Green sea turtles in the relatively cooler Pacific are known to haul themselves out of the water on remote islands to bask in the sun.[32] This behavior has only been observed in a few locations including the Galapagos, Hawaii, Europa Island, and parts of Australia.[32]
Diving physiology[edit]
Sea turtles are air breathing reptiles that have lungs, so they regularly surface to breathe. Sea turtles spend a majority of their time underwater, so they must be able to hold their breath for long periods.[33] Dive duration largely depends on activity. A foraging turtle may typically spend 5–40 min under water[33] while a sleeping sea turtle can remain under water for 4–7 hours.[34][35] Remarkably, sea turtle respiration remains aerobic for the vast majority of voluntary dive time.[33][35] When a sea turtle is forcibly submerged (e.g. entangled in a trawl net) its diving endurance is substantially reduced, so it is more susceptible to drowning.[33]
When surfacing to breathe, a sea turtle can quickly refill its lungs with a single explosive exhalation and rapid inhalation. Their large lungs permit rapid exchange of oxygen and avoid trapping gases during deep dives.
Fluorescence[edit]
Gruber and Sparks (2015)[36] have observed the first fluorescence in a marine tetrapod (four-limbed vertebrates).[37] Sea turtles are the first biofluorescent reptile found in the wild.
According to Gruber and Sparks (2015) fluorescence is observed in an increasing number of marine creatures (cnidarians, ctenophores, annelids, arthropods, and chordates) and is now also considered to be widespread in cartilaginous and ray-finned fishes.[36]
The two marine biologists accidentally made the observation in the Solomon Islands on a hawksbill sea turtle, one of the rarest and most endangered turtle species in the ocean, during a night dive aimed to film the biofluorescence emitted by small sharks and coral reefs. The role of biofluorescence in marine organisms is often attributed to a strategy for attracting prey or perhaps a way to communicate. It could also serve as a way of defense or camouflage for the sea turtle hiding during night amongst other fluorescent organisms like corals. Fluorescent corals and sea creatures are best observed during night dives with a blue LED light and with a camera equipped with an orange optical filter to capture only the fluorescence light.[38][39]
Ecology[edit]
Diet[edit]
The loggerhead, Kemp's ridley, olive ridley, and hawksbill sea turtles are omnivorous for their entire life. Omnivorous turtles may eat a wide variety of plant and animal life including decapods, seagrasses, seaweed, sponges, mollusks, cnidarians, echinoderms, worms and fish.[40][41][42][43] However some species specialize on certain prey.
The diet of green turtles changes with age.[44] Juveniles are omnivorous, but as they mature they become exclusively herbivorous.[41][44] This diet shift has an effect on the green turtle's morphology.[45][46] Green sea turtles have a serrated jaw that is used to eat sea grass and algae.[47]
Leatherback turtles feed almost exclusively on jellyfish and help control jellyfish populations.[48][49]
Hawksbills principally eat sponges, which constitute 70–95% of their diets in the Caribbean.[50]
Relationship with humans[edit]
Marine sea turtles are caught worldwide, although it is illegal to hunt most species in many countries.[51][52] A great deal of intentional marine sea turtle harvests worldwide are for food. Many parts of the world have long considered sea turtles to be fine dining. Ancient Chinese texts dating to the fifth century B.C.E. describe sea turtles as exotic delicacies.[53]Many coastal communities around the world depend on sea turtles as a source of protein, often harvesting several sea turtles at once and keeping them alive on their backs until needed. Coastal peoples gather sea turtle eggs for consumption.[54]
To a much lesser extent, specific species of marine sea turtles are targeted not for their flesh, but for their shells. Tortoiseshell, a traditional decorative ornamental material used in Japan and China, comes from the carapace scutes of the hawksbill sea turtle.[55][56] Ancient Greeksand ancient Romans processed sea turtle scutes (primarily from the hawksbill) for various articles and ornaments used by their elites, such as combs and brushes.[57] The skin of the flippers is prized for use as shoes and assorted leather goods.
The Moche people of ancient Peru worshipped the sea and its animals. They often depicted sea turtles in their art.[58]
Leatherback sea turtles enjoy immunity from the sting of the deadly box jellyfish and regularly eat them, helping keep tropical beaches safe for humans.
Beach towns, such as Tortuguero, Costa Rica, have transitioned from a tourism industry that made profits from selling sea turtle meat and shells to an ecotourism-based economy. Tortuguero is considered to be the founding location of sea turtle conservation. In the 1960s the cultural demand for sea turtle meat, shells, and eggs was quickly killing the once abundant sea turtle populations that nested on the beach. The Caribbean Conservation Corporation began working with villagers to promote ecotourism as a permanent substitute to sea turtle hunting. Sea turtle nesting grounds became sustainable. Tourists love to come and visit the nesting grounds, although it causes a lot of stress to the turtles because all of the eggs can get damaged or harmed.[59] Since the creation of a sea turtle, ecotourism-based economy, Tortugero annually houses thousands of tourists who visit the protected 22-mile (35 km) beach that hosts sea turtle walks and nesting grounds.[60][61]
Importance to ecosystems[edit]
Sea turtles play key roles in two habitat types: oceans and beaches/dunes.
In the oceans, sea turtles, especially green sea turtles, are one of very few creatures (manatees are another) that eat sea grass. Sea grass needs to be constantly cut short to help it grow across the sea floor. Sea turtle grazing helps maintain the health of the sea grass beds. Sea grass beds provide breeding and developmental grounds for numerous marine animals. Without them, many marine species humans harvest would be lost, as would the lower levels of the food chain. The reactions could result in many more marine species eventually becoming endangered or extinct.[62][citation needed]
Sea turtles use beaches and the lower dunes to nest and lay their eggs. Beaches and dunes are a fragile habitat that depend on vegetation to protect against erosion. Eggs, hatched or unhatched, and hatchlings that fail to make it into the ocean are nutrient sources for dune vegetation.[citation needed] Along a 20-mile (32 km) stretch of beach on the east coast of Florida sea turtles lay over 150,000 lb (68,000 kg) of eggs in the sand.[citation needed] Dune vegetation is able to grow and become stronger with the nutrients from sea turtle nests. Stronger vegetation and root systems help to hold the sand in the dunes and help protect the beach from erosion.[62]
Conservation status and threats[edit]
The IUCN Red List classifies three species of sea turtle as either "Endangered" or "Critically Endangered".[63] An additional three species are classified as "Vulnerable".[63] The flatback is considered as "Data Deficient", meaning that its conservation status is unclear due to lack of data.[63] All species of sea turtle are listed in CITESAppendix I, restricting international trade of sea turtles and sea turtle products.[4][64] However, the usefulness of global assessments for sea turtles has been questioned[65], particularly due to the presence of distinct genetic stocks and spatially separated regional management units (RMUs)[66]. Each RMU is subject to a unique set of threats that generally cross jurisdictional boundaries, resulting in some sub-populations of the same species' showing recovery while others continue to decline. This has triggered the IUCN to conduct threat assessments at the sub-population level for some species recently. These new assessments have highlighted an unexpected mismatch between where conservation relevant science has been conducted on sea turtles, and where these is the greatest need for conservation[67]. For example, as at August 2017, about 69% of studies using stable isotope analysis to understand the foraging distribution of sea turtles have been conducted in RMUs listed as 'Least Concern' by the IUCN[67].
Additionally, all populations of sea turtles that occur in United States waters are listed as threatened or endangered by the US Endangered Species Act (ESA).[68] The US listing status of the loggerhead is under review as of 2012.[68]
| IUCN Redlist | United States ESA* | |
|---|---|---|
| Green | Endangered[69] | Endangered: populations in Florida and Pacific coast of Mexico populations
Threatened: all other populations[70]
|
| Loggerhead | Vulnerable[71] | Endangered: NE Atlantic, Mediterranean, N Indian, N Pacific, S Pacific populations
Threatened: NW Atlantic, S Atlantic, SE Indo-Pacific, SW Indian populations[72]
|
| Kemp's ridley | Critically Endangered[73] | Endangered: all populations[74] |
| Olive ridley | Vulnerable[75] | Endangered: Pacific Coast of Mexico population
Threatened: all other populations[76]
|
| Hawksbill | Critically Endangered[77] | Endangered: all populations[78] |
| Flatback | Data Deficient[79] | N/A |
| Leatherback | Vulnerable[80] | Endangered: all populations[81] |
*The ESA manages sea turtles by population not by species.
Management[edit]
In the Caribbean, researchers are having some success in assisting a comeback.[82] In September 2007, Corpus Christi, Texas, wildlife officials found 128 Kemp's ridley sea turtle nests on Texas beaches, a record number, including 81 on North Padre Island (Padre Island National Seashore) and four on Mustang Island. Wildlife officials released 10,594 Kemp's ridleys hatchlings along the Texas coast this year.
The Philippines has had several initiatives dealing with the issue of sea turtle conservation. In 2007, the province of Batangas declared the catching and eating of sea turtles (locally referred to as Pawikans) illegal. However, the law seems to have had little effect as sea turtle eggs are still in demand in Batangan markets. In September 2007, several Chinese poachers were apprehended off the Turtle Islands in the country's southernmost province of Tawi-Tawi. The poachers had collected more than a hundred sea turtles, along with 10,000 sea turtle eggs.[83]
Evaluating the progress of conservation programs is difficult, because many sea turtle populations have not been assessed adequately.[84] Most information on sea turtle populations comes from counting nests on beaches, but this doesn’t provide an accurate picture of the whole sea turtle population.[85] A 2010 United States National Research Council report concluded that more detailed information on sea turtles’ life cycles, such as birth rates and mortality, is needed.[86]
Nest relocation may not be a useful conservation technique for sea turtles. In one study on the freshwater Arrau turtle (Podocnemis expansa) researchers examined the effects of nest relocation.[87] They discovered that clutches of this freshwater turtle that were transplanted to a new location had higher mortality rates and more morphological abnormalities compared to non transplanted clutches.[87] The results clearly demonstrate that humans should not manipulate or relocate clutches of that turtle, and impart strong evidence of the detrimental effects that human activity can cause.[citation needed]
Predators and disease[edit]
Most sea turtle mortality happens early in life. Sea turtles usually lay around one hundred eggs at a time, but on average only one of the eggs from the nest will survive to adulthood.[88] Raccoons, foxes, and seabirds may raid nests or hatchlings may be eaten within minutes of hatching as they make their initial run for the ocean.[89] Once in the water, they are susceptible to seabirds, large fish and even other turtles.
Adult sea turtles have few predators. Large aquatic carnivores such as sharks and crocodiles are their biggest threats; however, reports of terrestrial predators attacking nesting females are not uncommon. Jaguars have been reported to smash into the turtle's shell with its paw, and scoop out the flesh.[90]
Fibropapillomatosis disease causes tumors in sea turtles.
While many of the things that endanger sea turtles are natural predators,[89] increasingly many threats to the sea turtle species have arrived with the ever-growing presence of humans.[91]
Bycatch[edit]
One of the most significant and contemporary threats to sea turtles comes from bycatch due to imprecise fishing methods. Long-lining has been identified as a major cause of accidental sea turtle death.[92][93] There is also black-market demand for tortoiseshell for both decoration and supposed health benefits.[94]
Sea turtles must surface to breathe. Caught in a fisherman's net, they are unable to surface and thus drown. In early 2007, almost a thousand sea turtles were killed inadvertently in the Bay of Bengal over the course of a few months after netting.[95]
However, some relatively inexpensive changes to fishing techniques, such as slightly larger hooks and traps from which sea turtles can escape, can dramatically cut the mortality rate.[96][97] Turtle Excluder Devices (TEDs) have reduced sea turtle bycatch in shrimp nets by 97 percent.
.jpg)
Beach development[edit]
Beach development is another area which threatens sea turtles. Since many sea turtles return to the same beach each time to nest, development can disrupt the cycle.[citation needed] There has been a movement to protect these areas, in some cases by special police. In some areas, such as the east coast of Florida, conservationists dig up sea turtle eggs and relocate them to fenced nurseries to protect them from beach traffic.[citation needed]
Since hatchlings find their way to the ocean by crawling towards the brightest horizon, they can become disoriented on developed stretches of coastline.[citation needed] Lighting restrictions can prevent lights from shining on the beach and confusing hatchlings. Sea turtle-safe lighting uses red or amber LED light, invisible to sea turtles, in place of white light.[citation needed]
Poaching[edit]
Another major threat to sea turtles is black-market trade in eggs and meat. This is a problem throughout the world, but especially a concern in China, the Philippines, India, Indonesia and the coastal nations of Latin America. Estimates reach as high as 35,000 sea turtles killed a year in Mexico and the same number in Nicaragua. Conservationists in Mexico and the United States have launched "Don't Eat Sea Turtle" campaigns in order to reduce this trade in sea turtle products. These campaigns have involved figures such as Dorismar, Los Tigres del Norte and Maná. Sea turtles are often consumed during the Catholic season of Lent, even though they are reptiles, not fish. Consequently, conservation organizations have written letters to the Pope asking that he declare sea turtles meat.[98]
Marine debris[edit]
Another danger comes from marine debris, especially plastics which may be mistaken for jellyfish, and abandoned fishing nets in which they can become entangled.
Climate change[edit]
Climate change may also cause a threat to sea turtles. Since sand temperature at nesting beaches defines the sex of a sea turtle while developing in the egg, there is concern that rising temperatures may produce too many females.[citation needed] However, more research is needed to understand how climate change might affect sea turtle gender distribution and what other possible threats it may pose.[99]
Oil spills[edit]
Sea turtles are very vulnerable to oil pollution, both because of the oil's tendency to linger on the water's surface, and because oil can affect them at every stage of their life cycle.[100]Oil can poison the sea turtles upon entering their digestive system.
Rehabilitation[edit]
Injured sea turtles are rescued and rehabilitated (and, if possible, released back to the ocean) by professional organizations, such as the Gumbo Limbo Nature Center in Boca Raton, Florida, the Karen Beasley Sea Turtle Rescue and Rehabilitation Center in Surf City, North Carolina, and Sea Turtles 911 in Hainan, China.
One rescued sea turtle, named Nickel for the coin that was found lodged in her throat, lives at the Shedd Aquarium in Chicago.
Symbiosis with barnacles[edit]
Sea Turtles are believed to have a commensal relationship with some barnacles, in which the barnacles benefit from growing on turtles without harming them. Barnacles are small, hard shelled crustaceans found attached to multiple different substrates below or just above the ocean. The adult barnacle is a sessile organism, however in its larval stage it is planktonic and can move about the water column. The larval stage chooses where to settle and ultimately the habitat for its full adult life, which is typically between 5 and 10 years. However, estimates of age for a common sea turtle barnacle species, Chelonibia testudinaria, suggest that this species lives for at least 21 months[101], with individuals older than this uncommon. A favorite settlement for barnacle larvae is the shell or skin around the neck of sea turtles. The larvae glue themselves to the chosen spot, a thin layer of flesh is wrapped around them and a shell is secreted. Many species of barnacles can settle on any substrate, however some species of barnacles have an obligatory commensal relationship with specific animals, which makes finding a suitable location harder.[102] Around 29 species of "turtle barnacles" have been recorded. However it is not solely on sea turtles that barnacles can be found; other organisms also serve as barnacle’s settlements. These organisms include mollusks, whales, decapod crustaceans, manatees and several other groups related to these species.[103]
Sea turtle shells are an ideal habitat for adult barnacles for three reasons. Turtles tend to live long lives, >70 years, so barnacles do not have to worry about host death. However, mortality in sea turtle barnacles is often driven by their host shedding the scutes on which the barnacle is attached, rather than the death of the turtle itself[101]. Secondly, barnacles are suspension feeders. Sea turtles spend most of their lives swimming and following ocean currents and as water runs along the back of the turtle’s shell it passes over the barnacles, providing an almost constant water flow and influx of food particles. Lastly, the long distances and inter-ocean travel these sea turtles swim throughout their lifetime offers the perfect mechanism for dispersal of barnacle larvae. Allowing the barnacle species to distribute themselves throughout global waters is a high fitness advantage of this commensalism.[104]
This relationship however is not truly commensal. While the barnacles are not directly parasitic to their hosts, they have negative effects to the turtles on which they choose to reside. The barnacles add extra weight and drag to the sea turtle, increasing the energy it needs for swimming and affecting its ability to capture prey, with the effect increasing with the quantity of barnacles affixed to its back.[105]
Cenozoic
| Cenozoic Era 66 - 0 million years ago | |
Events of the Cenozoic
|
The Cenozoic Era ( /ˌsiːnəˈzoʊɪk, ˌsɛ-/;[1][2] also Cænozoic, Caenozoic or Cainozoic /ˌkaɪnəˈzoʊɪk, ˌkeɪ-/;[3][4] meaning "new life", from Greek καινόςkainós "new", and ζωή zōḗ "life"[5]) is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and covering the period from 66 million years ago to the present day.
The Cenozoic is also known as the Age of Mammals, because of the large mammals that dominated, such as Entelodon (a so-called "hell pig"), Paraceratherium (a hornless rhinoceros relative) and Basilosaurus (an early whale—despite the "-saurus" misnomer). The extinction of many large diapsid groups such as non-avian dinosaurs, Plesiosauria and Pterosauria allowed the mammals and birds to greatly diversify and become the world's predominant fauna.
Early in the Cenozoic, following the K-Pg event, the planet was dominated by relatively small fauna, including small mammals, birds, reptiles, and amphibians. From a geological perspective, it did not take long for mammals and birds to greatly diversify in the absence of the dinosaurs that had dominated during the Mesozoic. Some flightless birds grew larger than humans. These species are sometimes referred to as "terror birds," and were formidable predators. Mammals came to occupy almost every available niche (both marine and terrestrial), and some also grew very large, attaining sizes not seen in most of today's terrestrial mammals.
Following the Paleocene-Eocene Thermal Maximum, the Earth's climate began a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch. The continents also began looking roughly familiar at this time and moved into their current positions.
Contents
[hide]Subdivisions[edit]
The Cenozoic is divided into three periods: the Paleogene, Neogene, and Quaternary; and seven epochs: the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene. The Quaternary Period was officially recognized by the International Commission on Stratigraphy in June 2009,[6] and the former Tertiary Period was officially disused in 2004 because of the necessity to divide the Cenozoic into periods more like that of the previous Paleozoic and Mesozoic eras.[7][why?] The common use of epochs during the Cenozoic helps paleontologists better organize and group the many significant events that occurred during this comparatively short interval of time. There is also more detailed knowledge of this era than any other because of the relatively young, well-preserved rocks associated with it.
Paleogene Period[edit]
The Paleogene spans from the extinction of non-avian dinosaurs, 66 million years ago, to the dawn of the Neogene, 23.03 million years ago. It features three epochs: the Paleocene, Eocene and Oligocene.
The Paleocene epoch ranged from 66 million to 56 million years ago. It consists of modern placental mammals originated during this time.The Paleocene is a transitional point between the devastation that is the K-T extinction, to the rich jungles environment that is the Early Eocene. The Early Paleocene saw the recovery of the earth. The continents began to take their modern shape, but all the continents and subcontinent India were separated from each other. Afro-Eurasia was separated by the Tethys Sea, and the Americas were separated by the strait of Panama, as the isthmus had not yet formed. This epoch featured a general warming trend, with jungles eventually reaching the poles. The oceans were dominated by sharks[8] as the large reptiles that had once ruled became extinct. Archaic mammals filled the world such as creodonts (extinct carnivores, unrelated to existing Carnivora) and early primates that evolved during the Mesozoic, and as a result, there was nothing over 10 kilograms. Mammals were still quite small.[9]
The Eocene Epoch ranged from 56 million years to 33.9 million years ago. In the Early-Eocene, life was small and lived in cramped jungles, much like the Paleocene. There was nothing over the weight of 10 kilograms.[10] Among them were early primates, whales and horses along with many other early forms of mammals. At the top of the food chains were huge birds, such as Paracrax. The temperature was 30 degrees Celsius with little temperature gradient from pole to pole. In the Mid-Eocene, the Circumpolar-Antarctic current between Australia and Antarctica formed which disrupted ocean currents worldwide and as a result caused a global cooling effect, shrinking the jungles. This allowed mammals to grow to mammoth proportions, such as whales which, by that time, were almost fully aquatic. Mammals like Andrewsarchus were at the top of the food-chain. The Late Eocene saw the rebirth of seasons, which caused the expansion of savanna-like areas, along with the evolution of grass.[11][12] The end of the Eocene was marked by the Eocene-Oligocene extinction event, the European face of which is known as the Grande Coupure.
The Oligocene Epoch spans from 33.9 million to 23.03 million years ago. The Oligocene featured the expansion of grass which had led to many new species to evolve, including the first elephants, cats, dogs, marsupials and many other species still prevalent today. Many other species of plants evolved in this period too, such as the evergreen trees Conifersoriginated during the Carboniferous and dominated during the Mesozoic era. A cooling period was still in effect and seasonal rains were as well. Mammals still continued to grow larger and larger. Paraceratherium, the largest land mammal to ever live evolved during this period.[13]
Neogene[edit]
The Neogene spans from 23.03 million to 2.58 million years ago. It features 2 epochs: the Miocene, and the Pliocene.[14]
The Miocene epoch spans from 23.03 to 5.333 million years ago and is a period in which grass spread further, dominating a large portion of the world, at the expense of forests. Kelp forests evolved, encouraging the evolution of new species, such as sea otters. During this time, perissodactyla thrived, and evolved into many different varieties. Apes evolved into 30 species. The Tethys Sea finally closed with the creation of the Arabian Peninsula, leaving only remnants as the Black, Red, Mediterranean and Caspian Seas. This increased aridity. Many new plants evolved: 95% of modern seed plants evolved in the mid-Miocene.[15]
The Pliocene epoch lasted from 5.333 to 2.58 million years ago. The Pliocene featured dramatic climactic changes, which ultimately led to modern species and plants. The Mediterranean Sea dried up for several million years (because the ice ages reduced sea levels, disconnecting the Atlantic from the Mediterranean, and evaporation rates exceeded inflow from rivers). Australopithecus evolved in Africa, beginning the human branch. The isthmus of Panama formed, and animals migrated between North and South America, wreaking havoc on local ecologies. Climatic changes brought: savannas that are still continuing to spread across the world; Indian monsoons; deserts in central Asia; and the beginnings of the Sahara desert. The world map has not changed much since, save for changes brought about by the glaciations of the Quaternary, such as the Great Lakes, Hudson Bay, and the Baltic sea.[16][17]
Quaternary[edit]
The Quaternary spans from 2.58 million years ago to present day, and is the shortest geological period in the Phanerozoic Eon. It features modern animals, and dramatic changes in the climate. It is divided into two epochs: the Pleistocene and the Holocene.
The Pleistocene lasted from 2.58 million to 11,700 years ago. This epoch was marked by ice ages as a result of the cooling trend that started in the Mid-Eocene. There were at least four separate glaciation periods marked by the advance of ice caps as far south as 40 degrees N latitude in mountainous areas. Meanwhile, Africa experienced a trend of desiccation which resulted in the creation of the Sahara, Namib, and Kalahari deserts. Many animals evolved including mammoths, giant ground sloths, dire wolves, saber-toothed cats, and most famously Homo sapiens. 100,000 years ago marked the end of one of the worst droughts in Africa, and led to the expansion of primitive humans. As the Pleistocene drew to a close, a major extinction wiped out much of the world's megafauna, including some of the hominid species, such as Neanderthals. All the continents were affected, but Africa to a lesser extent. It still retains many large animals, such as hippos.[18]
The Holocene began 11,700 years ago and lasts to the present day. All recorded history and "the history of the world" lies within the boundaries of the Holocene epoch.[19] Human activity is blamed for a mass extinction that began roughly 10,000 years ago, though the species becoming extinct have only been recorded since the Industrial Revolution. This is sometimes referred to as the "Sixth Extinction". Over 322 species have become extinct due to human activity since the Industrial Revolution.[20][21]
Tectonics[edit]
Geologically, the Cenozoic is the era when the continents moved into their current positions. Australia-New Guinea, having split from Pangea during the early Cretaceous, drifted north and, eventually, collided with South-east Asia; Antarctica moved into its current position over the South Pole; the Atlantic Ocean widened and, later in the era (2.8 million years ago), South America became attached to North America with the isthmus of Panama.
India collided with Asia 55 to 45 million years ago creating the Himalayas; Arabia collided with Eurasia, closing the Tethys Ocean and creating the Zagros Mountains, around 35 million years ago.[22]
Climate[edit]
The Paleocene–Eocene Thermal Maximum at about 55.5 million years ago was a significant global warming event; however, since the Azolla event of 49 million years ago, the Cenozoic Era has been a period of long-term cooling. After the tectonic creation of Drake Passage at 41 million years ago, when South America fully detached from Antarctica during the Oligocene, the climate cooled significantly due to the advent of the Antarctic Circumpolar Current which brought cool deep Antarctic water to the surface. The cooling trend continued in the Miocene, with relatively short warmer periods. When South America became attached to North America creating the Isthmus of Panama around 2.8 million years ago, the Arctic region cooled due to the strengthening of the Humboldt and Gulf Stream currents,[23] eventually leading to the glaciations of the Quaternary ice age, the current interglacial of which is the Holocene Epoch. Recent analysis of the geomagnetic reversal frequency, oxygen isotope record, and tectonic plate subduction rate, which are indicators of the changes in the heat flux at the core mantle boundary, climate and plate tectonic activity, shows that all these changes indicate similar rhythms on million years’ timescale in the Cenozoic Era occurring with the common fundamental periodicity of ∼13 Myr during most of the time.[24]
Life[edit]
During the Cenozoic, mammals proliferated from a few small, simple, generalized forms into a diverse collection of terrestrial, marine, and flying animals, giving this period its other name, the Age of Mammals, despite the fact that there are more than twice as many bird species as mammal species. The Cenozoic is just as much the age of savannas, the age of co-dependent flowering plants and insects, and the age of birds.[25] Grass also played a very important role in this era, shaping the evolution of the birds and mammals that fed on it. One group that diversified significantly in the Cenozoic as well were the snakes. Evolving in the Cenozoic, the variety of snakes increased tremendously, resulting in many colubrids, following the evolution of their current primary prey source, the rodents.
In the earlier part of the Cenozoic, the world was dominated by the gastornithid birds, terrestrial crocodiles like Pristichampsus, and a handful of primitive large mammal groups like uintatheres, mesonychids, and pantodonts. But as the forests began to recede and the climate began to cool, other mammals took over.
The Cenozoic is full of mammals both strange and familiar, including chalicotheres, creodonts, whales, primates, entelodonts, saber-toothed cats, mastodons and mammoths, three-toed horses, giant rhinoceros like Indricotherium, the rhinoceros-like brontotheres, various bizarre groups of mammals from South America, such as the vaguely elephant-like pyrotheres and the dog-like marsupial relatives called borhyaenids and the monotremes and marsupials of Australia.
.jpg)
No comments:
Post a Comment