Archive for the ‘Sea Turtle Camp News’ Category

Cnidarians

Wednesday, April 16th, 2014

jellyCnidarians are distinguished by their jelly like bodies and are composed of nonliving gelatinous matter called mesoglea suspended between two layers of epithelium. These animals have two body forms, one with mobility and one without. Both the swimming medusa and the sessile polyp display radial symmetry.

Cnidarians are classified into four main groups; Anthozoa, Scyphozoa, Cubozoa, and Hydrozoa.

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Anthozoa means “flower animals” and encompass  sea anemones, corals, and sea pens. Scyphozoans refer to  “true jellies”, while Cubozoans are a group of cube-shaped jellies (a few of which a known to be the most venomous creatures in the world). Hydrozoans are a diverse group, including both fresh and marine forms. Hydrozoans can be sessile or free swimming and incorporate animals from hydras to the Portuguese Man o’War

Feeding is similar in both forms. A mouth is surrounded by tentacles layered with specialized cells called cnidocytes. Cnidocytes or “nettle cells” fire like harpoons and are used mainly to capture prey. Cnidocytes can only fire once and then must be replaced,  All cnidarians can regenerate to allow for reproduction (asexual) and recovery from injury.

lionThere are three know types of cnidocytes; Nematocysts which inject venom using a barb, spirocysts which entangle prey by use of a sticky secretion and ptychocysts which are used for protection not the acquisition of prey.

Species obtain nutrients in many different ways, some use predation, some use absorption, and other filer feed. Most, however, obtain the majority of the required nutrients through predations. The majority uses their cnidocytes to capture prey, a chemical indicator triggers by the release of fluid from the injured prey tells the tentacles to pass the food along to the mouth.The best part about cnidarians is that they are sea turtles favorite treat!

Loggerhead sea turtle (Caretta caretta)

Wednesday, April 9th, 2014

Loggerhead head i.d. - Marlene RobinsonLoggerhead turtles are the most abundant of all the marine turtle species in U.S. waters. Their distinctively large head and the reddish-brown color of their carapace makes them easy to identify. Loggerheads are one of the largest of the hard-shelled turtles and their range is enormous, encompassing all but the most frigid waters of the world’s oceans. In the Atlantic Ocean, the greatest concentration of loggerheads is along the southeastern coast of North America and in the Gulf of Mexico.

As adults their shell reaches an average length of 3 feet and they weigh around 250 pounds, however the largest specimens recorded weighed in at over 1000 pounds! Loggerheads are primarily carnivores, munching jellyfish, conchs, crabs, and even fish, but  they will eat seaweed and sargassum occasionally. They have a string jaw which is adapted well to crushing the the hard outer shell their favorite treats.

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This species of turtle  has a low reproductive rate as sexual maturity is reached between 17-33 years of age. The female will lay 3-4 clutches of around 115 eggs every 3-4 years, it is estimated that only 1 in 10,000 of these hatchlings survive into adulthood.

Loggerheads are listed as an endangered species. The population decline is a direct result of pollution, poaching, shrimp/fish trawling, and development in their nesting areas. Males turtles never return to shore after hatching and females only returning during nesting intervals, therefore it can be very difficult to accurately gauge a species total populations.

Flatback Sea Turtle (Natator depressus)

Wednesday, April 2nd, 2014

fffffffThe flatback derives its name from its flat oval carapace. The edge of this species shell are folded upward  and covered with thin, waxy scutes. Flatbacks are olive-gray with pale brown with yellow tones underneath and flippers that are creamy white. This is the only species of sea turtle that does not migrate great distances. Their range is limited to the Pacific waters around Australia and Papua New Guinea. They prefer turbid inshore waters, bays, coastal reefs, and grassy shallows.

Flatbacks nest four times per season every 16–17 days and lay only  around 50  to 70  eggs at time. This species eggs and the subsequent hatchlings are quite large when compared to other species. The eggs incubate for 55 days and when the hatchlings emerge, they scurry to the sea like any turtle would. Juvenile flatbacks are thought to lack a pelagic (open ocean) existence, instead they remain in near shore waters with the adults.

The flatbacks are protected by The Australian government. Small numbers of these turtles are still allowed to be taken for harvest by aboriginal tribes. Threats facing these turtles include entanglement in prawn trawls and pollution in near shore environments where flatbacks feed and mate.

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Olive ridley Sea Turtle (Lepidochelys olivacea)

Wednesday, March 26th, 2014

Lepidochelys_olivaceaThe olive ridley is the most numerous of all the sea turtle species and is a medium-sized species of sea turtle found mainly in the warm and tropical waters, primarily in the Pacific and Indian Oceans. It is named for its olive green colored shell, which in shape is very similar to the Kemp’s ridley sea turtle. but with a slightly smaller head and a deeper disk-shaped shell.

Olive ridleys, like the Kemps, nest every year in arribadas. However, these arribadas occur at night on a 28-day lunar, unlike the daytime arribadas of the Kemp’s ridley. The arribadas of this species are almost smaller, then their cousins, usually  only involving around 1,000 nesting females at a time. Females will nest 2 times each season and lays an average of 105 eggs in each nest. The two popular nesting beaches for Olive ridleys are Ostional and Playa Grande in Costa Rica.

olive-ridley-arribadasThe Olive Ridley has many known natural predators. As eggs the main threats are from land animals like raccoons, coyotes, feral dogs and pigs, opossums, ghost crabs, and snakes. Hatchlings are preyed upon as they travel across the beach to the water by bird, crabs, and raccoons. Adults they have few natural predators, but boat strikes and inadvertent submersion or capturing in ocean fishing gear do negatively impact the overall population Oddly enough, the greatest single cause of olive ridley egg loss results from arribadas, in which the density of nesting females is so high, previously laid nests are inadvertently dug up and destroyed by other nesting females.

Kemp’s Ridley Sea Turtle (Lepidochelys kempii)

Wednesday, March 19th, 2014

kemps_ridley_cory_wilsonThey are named Kemp’s after Richard Kemp, who helped discover and study them. Their carapace oval in shape and olive green to gray in color while their plastron is typically a light yellow. The Kemp’s ridley is the most endangered sea turtle; their decline resulted from egg poaching and interactions with the fisheries industry, primarily becoming trapped in trawl nets.

This is also the smallest of the sea turtles, with adults reaching  only about 2 feet in length and weighing just over 100 pounds maximum. They have powerful jaws, allowing them to feed on crabs, clams, mussels, shrimp, snails, sea urchins, sea stars, fish and some saltwater plants.

Kemp’s ridley turtles follow two major migratory routes in the Gulf of Mexico: one northward to the Mississippi area, and the other southward to the Campeche Bank, near the Yucatan Peninsula.

downloadNinety-five percent of all nesting occurs in daylight on Rancho Nuevo beach on the eastern coast of Mexico between May and July. Female Kemp’s typically lay three clutches of approximately 100 eggs, which incubate for 50-60 days. This species comes ashore in mass synchronized nesting called arribadas, Spanish for “the arrival.” In 1947, an estimated 42,000 nesting females were documented on film as they were coming ashore to lay eggs on a single day! In 1995, only 1,400 ridleys nested at Rancho Nuevo.