Cheloniidae

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Cheloniid sea turtles
Temporal range: Late Cretaceous-Holocene, 72–0  Ma
Green turtle swimming over coral reefs in Kona.jpg
A green sea turtle, a species of the family Cheloniidae, swimming over coral reefs in Kona, Hawaii
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Superfamily: Chelonioidea
Family: Cheloniidae
Oppel, 1811 [1]
Type genus
Chelonia
Brongniart, 1800
Genera

See text.

Synonyms [1]
  • Chelonii - Oppel, 1811
  • Cheloniadae - Gray, 1825
  • Carettidae - Gray, 1825
  • Mydae - Ritgen, 1828
  • Chelonidae - Bonaparte, 1832
  • Cheloniidae - Cope, 1868

Cheloniidae is a family of typically large marine turtles that are characterised by their common traits such as, having a flat streamlined wide and rounded shell and almost paddle-like flippers for their forelimbs. They are the only sea turtles to have stronger front limbs than back limbs. [2] The six species that make up this family are: the green sea turtle, loggerhead sea turtle, olive ridley sea turtle, hawksbill sea turtle, flatback sea turtle and the Kemp's ridley sea turtle. [3]

Contents

Morphology

In contrast to their earth-bound relatives, tortoises, sea turtles do not have the ability to retract their heads into their shells. Their plastron, which is the bony plate making up the underside of a turtle or tortoise's shell, is comparably more reduced from other turtle species and is connected to the top part of the shell by ligaments without a hinge separating the pectoral and abdominal plates of the plastron. Sizes among the seven species of sea turtles range from 71 to 213 cm; [2] for example, the smallest turtle species in the family Cheloniidae, the Kemp's Ridley, only has a shell size of about 75 cm and a weight of 50 kg. All species have a distinct hardened shell. [4]

Reproduction and life cycle

Reproductive behaviors among the different species of sea turtles are similar, with slight differences in each of the species. The females come to shore and bury their clutch of eggs on beaches or sandy environments typically at night and well away from the high tide line of the shore. Most females nest only once every three to four years and most species have two to four egg laying time periods per nesting season, which is from spring to late fall. A common number of eggs laid in a nest is often about 100 eggs per clutch. The incubation period of some turtles can range anywhere from 50 to 60 days. The development of the eggs is dependent on the temperature of the environment that they were buried in, with warmer climates bringing about an earlier emergence by the hatchlings. The timing of sea turtle hatching tends to be almost synchronous among the whole clutch of eggs, with just about all the eggs in the nest hatching within the same time. This is thought to aid the process of the hatchlings unburying themselves from the sand and most often occurs at night time. Temperature has also been linked to the likeliness of hatching's sex, warmer temperature more likely to produce females and colder temperatures more commonly producing males. [5]

Habitat and ecology

The habitat range of sea turtles, in general, is known to be far reaching into warmer temperatures and the tropical and subtropical areas of the Pacific and Atlantic Oceans and is even also found in warmer seas such as the Mediterranean Sea. [6] Within these temperamental biomes, sea turtles frequent near by the coastlines when nesting, and spend most of their lives swimming out in waters over the continental shelf when feeding. [7] Travelling throughout the oceans has been reported in olive ridley sea turtles but more often than not, they tend to frequent bays and estuaries. The diets of all the sea turtle species, except for the Green Sea Turtle, which is only herbivorous from hatchling to juvenile, are mostly carnivorous, with some herbivorous tendencies. Sea turtles feed mainly on sea sponges, jellyfish, mollusks and barnacles, sea urchins, and even fish. The green sea turtle, on the other hand, feeds primarily on many different types of sea grasses. [8]

Conservation status and significance to humans

The conservation status of each of the seven turtle species are either endangered, threatened or data deficient (Flatback). The green and loggerhead sea turtles are categorized as endangered, olive ridley are classified as vulnerable, Kemp's ridley, and hawksbill sea turtles are critically endangered and the flatback sea turtle does not have enough data to draw an accurate conclusion on conservation status. [9]

Most do not reach sexual maturity before becoming prey to other organisms, or being caught by humans either intentionally or as bycatch by commercial fishing operations. Their slow maturity rate, which most of the time means about 10 or 15 years, does not allow the turtles which have been caught to have fully reproductively matured and to have produced hatchlings of their own. International legislation has been put into place to attempt to reduce the number of sea turtle deaths but this does not deter the demand for the consumption of turtle eggs around the world, and some are hunted for their shells.

In addition to this, turtles face another threat which has been theorized as being linked to human pollution. A growing number of turtles have been found with fibropapillomatosis, fibrous tumor growths on their skin, mouths, and even internal organs. In some areas the number of infected turtles is over 70%. It is unknown what the effects of the growths will have in the long term for sea turtle populations. [10]

Sea turtles play a very important part in marine ecosystems. They maintain the balance of health of sea grasses and reefs, which in turn benefit the likes of shrimp, lobsters, and tunas. They are also the last living members of the seafaring category of marine reptiles that have been in existence on Earth for at least the past 100 million years. They are also highly significant to multiple cultures and are also popular animals in tourism, which gives a higher importance to their conservation. [11]

Classification

Extant genera

Cladogram

Below is a cladogram showing the phylogenetic relationships of living and extinct sea turtles in the family Cheloniidae based on Lynch and Parham (2003) [12] and Parham and Pyenson (2010). [13]

Pancheloniidae  (=Cheloniidae sensu lato) 

Toxochelys

Mexichelys

Lophochleyinae

Euclastes

Argillochelys

Eochelone

Erquelinnesia

Pacifichelys

Puppigerus

 Cheloniidae (sensu stricto) 

Syllomus

Procolpochelys

Chelonia mydas Erpetologie generale, ou, Histoire naturelle complete des reptiles (Chelonia mydas).jpg

Natator depressus

Eretmochelys imbricata Erpetologie generale, ou, Histoire naturelle complete des reptiles (Eretmochelys imbricata).jpg

  Carettini  
  Lepidochelys  

Lepidochelys kempii

Lepidochelys olivacea

Caretta caretta

Extinct genera

Related Research Articles

<span class="mw-page-title-main">Sea turtle</span> Reptiles of the superfamily Chelonioidea

Sea turtles, sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, Kemp's ridley, and olive ridley. Six of the seven sea turtle species, all but the flatback, are present in U.S. waters, and are listed as endangered and/or threatened under the Endangered Species Act. All but the flatback turtle are listed as threatened with extinction globally on the IUCN Red List of Threatened Species. The flatback turtle is found only in the waters of Australia, Papua New Guinea, and Indonesia.

<span class="mw-page-title-main">Olive ridley sea turtle</span> One of the most abundant living sea turtle in the world

The olive ridley sea turtle, also known commonly as the Pacific ridley sea turtle, is a species of turtle in the family Cheloniidae. The species is the second-smallest and most abundant of all sea turtles found in the world. L. olivacea is found in warm and tropical waters, primarily in the Pacific and Indian Oceans, but also in the warm waters of the Atlantic Ocean.

<span class="mw-page-title-main">Loggerhead sea turtle</span> Species of marine reptile distributed throughout the world

The loggerhead sea turtle is a species of oceanic turtle distributed throughout the world. It is a marine reptile, belonging to the family Cheloniidae. The average loggerhead measures around 90 cm (35 in) in carapace length when fully grown. The adult loggerhead sea turtle weighs approximately 135 kg (298 lb), with the largest specimens weighing in at more than 450 kg (1,000 lb). The skin ranges from yellow to brown in color, and the shell is typically reddish brown. No external differences in sex are seen until the turtle becomes an adult, the most obvious difference being the adult males have thicker tails and shorter plastrons than the females.

<span class="mw-page-title-main">Kemp's ridley sea turtle</span> Species of sea turtle

Kemp's ridley sea turtle, also called the Atlantic ridley sea turtle, is the rarest species of sea turtle and is the world's most endangered species of sea turtle. It is one of two living species in the genus Lepidochelys. The species primarily occupies habitat around the Gulf of Mexico though their migrations into the Atlantic are being affected by rising temperatures. Kemp's ridley sea turtles are currently listed as endangered under the Endangered Species Act (ESA), and current conservation efforts attempt to rebuild population numbers. Human activity, including but not limited to habitat destruction, climate change, and oil spills, threaten populations.

<span class="mw-page-title-main">Green sea turtle</span> Species of large sea reptile

The green sea turtle, also known as the green turtle, black (sea) turtle or Pacific green turtle, is a species of large sea turtle of the family Cheloniidae. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans, but it is also found in the Indian Ocean. The common name refers to the usually green fat found beneath its carapace, not to the color of its carapace, which is olive to black.

<span class="mw-page-title-main">Flatback sea turtle</span> Species of turtle

The Australian flatback sea turtle is a species of sea turtle in the family Cheloniidae. The species is endemic to the sandy beaches and shallow coastal waters of the Australian continental shelf. This turtle gets its common name from the fact that its shell has a flattened or lower dome than the other sea turtles. It can be olive green to grey with a cream underside. It averages from 76 to 96 cm in carapace length and can weigh from 70 to 90 kg. The hatchlings, when emerging from nests, are larger than other sea turtle hatchlings when they hatch.

<span class="mw-page-title-main">Memorandum of Understanding on the Conservation and Management of Marine Turtles and their Habitats of the Indian Ocean and South-East Asia</span>

The Memorandum of Understanding on the Conservation and Management of Marine Turtles and their Habitats of the Indian Ocean and South-East Asia is an intergovernmental agreement that aims to protect, conserve, replenish and recover sea turtles and their habitats in the Indian Ocean and South-East Asian region, working in partnership with other relevant actors and organizations.

<span class="mw-page-title-main">Reptiles of New Zealand</span>

The extant (living) reptiles of New Zealand consist of numerous species of terrestrial lizards and the lizard-like tuatara, and several species of sea turtles and sea snakes. All but one species are native to New Zealand, and all but one of the terrestrial species are endemic to New Zealand, that is, they are not found in any other country. Many species of foreign reptiles enter New Zealand through accidental importation or smuggling, but only the Australian native Lampropholis delicata has become established in the wild, and it is considered an invasive pest.

<span class="mw-page-title-main">Threats to sea turtles</span>

Threats to sea turtles are numerous and have caused many sea turtle species to be endangered. Of the seven extant species of sea turtles, six in the family Cheloniidae and one in the family Dermochelyidae, all are listed on the IUCN Red List of Endangered Species. The list classifies six species of sea turtle as "threatened", two of them as "critically endangered", one as "endangered" and three as "vulnerable". The flatback sea turtle is classified as "data deficient" which means that there is insufficient information available for a proper assessment of conservation status. Although sea turtles usually lay around one hundred eggs at a time, on average only one of the eggs from the nest will survive to adulthood. While many of the things that endanger these hatchlings are natural, such as predators including sharks, raccoons, foxes, and seagulls, many new threats to the sea turtle species are anthropogenic.

<span class="mw-page-title-main">Sea turtle migration</span> Seasonal movement of sea turtles

Sea turtle migration is the long-distance movements of sea turtles notably the long-distance movement of adults to their breeding beaches, but also the offshore migration of hatchings. Sea turtle hatchings emerge from underground nests and crawl across the beach towards the sea. They then maintain an offshore heading until they reach the open sea. The feeding and nesting sites of adult sea turtles are often distantly separated meaning some must migrate hundreds or even thousands of kilometres.

<span class="mw-page-title-main">Gnaraloo Turtle Conservation Program</span> Environmental organization

The Gnaraloo Turtle Conservation Program (GTCP) is an environmental organisation based at the Gnaraloo pastoral station and run by the Gnaraloo Wilderness Foundation, a not-for-profit organisation. The aim of the GTCP is to identify, monitor and protect the nesting beaches of loggerhead sea turtles found at two locations on the Gnaraloo coastline. These two rookeries contribute to the South-East Indian Ocean subpopulation of loggerhead turtles, with other major nesting sites for this sub-population at Dirk Hartog island and Exmouth. This is within the southern boundaries of the Ningaloo Coast marine area, a UNESCO World Heritage Site.

<span class="mw-page-title-main">Amazon–Orinoco–Southern Caribbean mangroves</span>

The Amazon–Orinoco–Southern Caribbean mangroves (NT1401) is an ecoregion along the coasts of Colombia, Venezuela, Guyana, Suriname, French Guiana and Brazil.

Thamihla Kyun Wildlife Sanctuary is a protected area in Myanmar, located on the 0.88 km2 (0.34 sq mi) small uninhabited Diamond Island near the mouth of Pathein River. It was established in 1970 and is part of Ngaputaw Township in Ayeyarwady Region. It is managed by the Forest Department.

The Northern Monsoon Current coast is a marine ecoregion along the eastern coast of Africa. It extends along a portion of the coasts of Somalia and Kenya, from south of Lamu in Kenya to north of Mogadishu in Somalia. It adjoins the Central Somali coast ecoregion to the north, and the East African coral coast ecoregion to the south.

<span class="mw-page-title-main">Kalba Mangrove reserve</span> Protected area in the emirate of Sharjah

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References

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  2. 1 2 Pecor, Keith. "Cheloniidae". Animal Diversity Web. Retrieved 2022-10-29.
  3. "Cheloniidae - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-10-29.
  4. "Information About Sea Turtles: Leatherback Sea Turtle – Sea Turtle Conservancy" . Retrieved 2024-02-01.
  5. "Sea Turtle Species" World Wildlife https://www.worldwildlife.org/species/sea-turtle
  6. "Seaturtles (Cheloniidae) | Encyclopedia.com". www.encyclopedia.com. Retrieved 2024-02-01.
  7. "Sea Turtles- Cheloniidae Over View" Encyclopedia of Life http://eol.org/pages/8123/overview
  8. "Green Sea Turtle" National Geographic
  9. "Sea Turtle Threats" See Turtles http://www.seeturtles.org/sea-turtles-threats/
  10. "Fibropapillomatosis" Florida Fish and Wildlife Conservation Commission http://myfwc.com/research/wildlife/sea-turtles/threats/fibropapillomatosis/
  11. "Sea Turtle" World Wildlife Fund https://www.worldwildlife.org/species/sea-turtle
  12. Lynch, S.C.; Parham, J.F. (2003). "The first report of hard-shelled sea turtles (Cheloniidae sensu lato) from the Miocene of California, including a new species (Euclastes hutchisoni) with unusually plesiomorphic characters" (PDF). PaleoBios. 23 (3): 21–35.[ permanent dead link ]
  13. James F. Parham; Nicholas D. Pyenson (2010). "New Sea Turtle from the Miocene of Peru and the Iterative Evolution of Feeding Ecomorphologies since the Cretaceous". Journal of Paleontology. 84 (2): 231–247. Bibcode:2010JPal...84..231P. doi:10.1666/09-077R.1. S2CID   62811400.
  14. Myers, T.S., Polcyn M.J., Mateus O., Vineyard D.P., Gonçalves A.O., & Jacobs L.L. (2017). "A new durophagous stem cheloniid turtle from the lower Paleocene of Cabinda, Angola." Papers in Palaeontology 1-16.
  15. H. F. Kaddumi (2006). "A new genus and species of gigantic marine turtles (Chelonioidea: Cheloniidae) from the Maastrichtian of the Harrana Fauna-Jordan" (PDF). PalArch's Journal of Vertebrate Palaeontology. 3 (1): 1–14. Archived from the original (PDF) on 2012-02-24. Retrieved 2010-02-04.
  16. Danilov, I.G.; Averianov, A.O; Yarkov, A.A. (2010). "Itilochelys rasstrigin gen. et sp. nov., a new hard-shelled sea turtle (Cheloniidae sensu lato) from the Lower Palaeocene of Volgograd Province, Russia" (PDF). Proceedings of the Zoological Institute RAS. 314 (1): 24–41. doi:10.31610/trudyzin/2010.314.1.24. S2CID   250006012.

Bibliography