SEA TURTLESSEA TURTLES

MR. JEAN MR. JEAN

BIOLOGYBIOLOGY

ANNIE TRAN ANNIE TRAN

GENERAL INFO.GENERAL INFO.• Turtles have been on earth since the first Turtles have been on earth since the first

dinosaurs.  Sea turtles specifically, salt water dinosaurs.  Sea turtles specifically, salt water turtles) are ancient creatures and are part of the turtles) are ancient creatures and are part of the reptile family. reptile family.

• Sea turtles are generally solitary creatures. They Sea turtles are generally solitary creatures. They are some of the largest turtles in the world and live are some of the largest turtles in the world and live in almost every ocean of the world! Their smooth in almost every ocean of the world! Their smooth shells and flippers help them speed through the water shells and flippers help them speed through the water as fast as 24 km per hour. These long-distance as fast as 24 km per hour. These long-distance travelers have been known to swim up to 4,828 km. travelers have been known to swim up to 4,828 km.

• Although sea turtles cannot bring in their heads into Although sea turtles cannot bring in their heads into their shells, the adults are protected from predators their shells, the adults are protected from predators by their shells, large size, and thick scaly skin on by their shells, large size, and thick scaly skin on their heads and necks. their heads and necks.

• There also seven different types of sea turtle There also seven different types of sea turtle species: the Australian Flatback turtle, Green sea species: the Australian Flatback turtle, Green sea turtle, Hawksbill turtle, Kemp’s Ridley, Leatherback turtle, Hawksbill turtle, Kemp’s Ridley, Leatherback turtle, Logger head turtle and Olive Ridley turtle. turtle, Logger head turtle and Olive Ridley turtle.

SEVEN SEA TURTLE SPECIES:SEVEN SEA TURTLE SPECIES:AUSTRALIAN FLATBACK TURTLE:AUSTRALIAN FLATBACK TURTLE: This medium- This medium-sized sea turtle, nest on beaches in sized sea turtle, nest on beaches in unpopulated areas of the northern coast unpopulated areas of the northern coast of Australia. Saltwater crocodiles, of Australia. Saltwater crocodiles, lizards and foxes, sometimes eat small lizards and foxes, sometimes eat small adult turtles while they are nesting.adult turtles while they are nesting.

GREEN SEA TURTLE:GREEN SEA TURTLE: This medium-to-large This medium-to-large sea turtle gets its name from the green sea turtle gets its name from the green color of its body fat. Its smooth olive-color of its body fat. Its smooth olive-brown carapace is heart shaped. Its brown carapace is heart shaped. Its jagged beak, notched like the edge of a jagged beak, notched like the edge of a saw, helps it feed on turtle grass and saw, helps it feed on turtle grass and other marine plants. other marine plants.

OLIVE RIDLEY:OLIVE RIDLEY: Also known as the Pacific Also known as the Pacific Ridley, is a small sea turtle which can Ridley, is a small sea turtle which can grow up to 70cm long. They are speedy grow up to 70cm long. They are speedy nesters who only spend about 45 minutes nesters who only spend about 45 minutes on the beach to lay its eggs. on the beach to lay its eggs.

SEVEN SEA TURTLE SPECIES:SEVEN SEA TURTLE SPECIES:

HAWKSBILL TURTLE:HAWKSBILL TURTLE: These turtles have These turtles have shield-shaped shells which are found shield-shaped shells which are found in the tropical waters around the in the tropical waters around the world. The Hawksbill Turtle gets its world. The Hawksbill Turtle gets its name for its birdlike beak and name for its birdlike beak and usually nests near its feeding ground usually nests near its feeding ground and mates in shallow water off the and mates in shallow water off the nesting beach. Hawksbills climb overnesting beach. Hawksbills climb over

LOGGERHEAD TURTLE:LOGGERHEAD TURTLE: Are known for Are known for its massive reddish brown head. The its massive reddish brown head. The large omnivorous loggerhead sea large omnivorous loggerhead sea turtle eats: fish, jellyfish, turtle eats: fish, jellyfish, mussels, clams, squid, seaweed and mussels, clams, squid, seaweed and marine grasses. The loggerhead marine grasses. The loggerhead travels widely and has been found travels widely and has been found as 800 km offshore.as 800 km offshore.

reefs and rocks to nest among the roots of vegetation reefs and rocks to nest among the roots of vegetation on beaches.on beaches.

SEVEN SEA TURTLE SPECIES:SEVEN SEA TURTLE SPECIES:KEMP’S RIDLEY TURTLE:KEMP’S RIDLEY TURTLE: Also known as the Atlantic Ridley Also known as the Atlantic Ridley turtle, is the world’s most endangered and one of the turtle, is the world’s most endangered and one of the smallest sea turtles. They can reach about 55 to 65 cm and smallest sea turtles. They can reach about 55 to 65 cm and 30 to 50 kg. Little is known of its habits, only that 30 to 50 kg. Little is known of its habits, only that between April and mid-August, the turtles nest in large between April and mid-August, the turtles nest in large groups called ‘Arribadas’ (Spanish for “arrival”), in only groups called ‘Arribadas’ (Spanish for “arrival”), in only one place in the world, a beach near Rancho Nuevo, Mexico. one place in the world, a beach near Rancho Nuevo, Mexico. In 1947, over 41,000 female Kemp’s Ridley turtles nested In 1947, over 41,000 female Kemp’s Ridley turtles nested on that beach in a single day but later in 1992, only 500 on that beach in a single day but later in 1992, only 500 came to nest. came to nest. LEATHER BACK TURTLE:LEATHER BACK TURTLE: The largest of The largest of all sea turtles which can all sea turtles which can grow to over 2 grow to over 2 metres long. These tireless metres long. These tireless swimmers have been found throughout swimmers have been found throughout the world’s oceans.Leatherbacks can the world’s oceans.Leatherbacks can also dive to great depths, as far as also dive to great depths, as far as 900 metres, probably in search for 900 metres, probably in search for their favourite food, the jellyfish. their favourite food, the jellyfish.

• Male and female sea turtles do not differ or have much Male and female sea turtles do not differ or have much sexual dimorphism, until they reach maturity.sexual dimorphism, until they reach maturity.

• It is difficult to differ female and male turtles when It is difficult to differ female and male turtles when they are differentiation in hatchlings, juveniles and they are differentiation in hatchlings, juveniles and sub-adults, without internal examination. sub-adults, without internal examination.

• When approaching maturity, adult male sea turtles have When approaching maturity, adult male sea turtles have longer, thicker tails, while female sea turtles have longer, thicker tails, while female sea turtles have short and stubby tails. This is because the male short and stubby tails. This is because the male reproductive organ is implant in the base of the tail. reproductive organ is implant in the base of the tail. In males, the tail may extend beyond the hind In males, the tail may extend beyond the hind flippers. flippers.

• For some turtles, the claws on the fore flippers of For some turtles, the claws on the fore flippers of males are extended and curved, which may help in males are extended and curved, which may help in grasping the females' shells during mating. grasping the females' shells during mating.

SEXUAL DIMORPHISM”SEXUAL DIMORPHISM”

PHYSICAL APPEARANCEPHYSICAL APPEARANCE

COURTSHIP AND MATING#COURTSHIP AND MATING#Courtship and mating for most sea turtles is believed to Courtship and mating for most sea turtles is believed to occur during a limited "receptive" period prior to the occur during a limited "receptive" period prior to the female's first nesting appearance. Afterwards, only females female's first nesting appearance. Afterwards, only females come ashore to nest. Males almost never return to land once come ashore to nest. Males almost never return to land once they leave the sand of their natal beach. they leave the sand of their natal beach. During mating season, males may court a female by nuzzling During mating season, males may court a female by nuzzling her head or by gently biting the back of her neck and rear her head or by gently biting the back of her neck and rear flippers. If the female does not flee, the male attaches flippers. If the female does not flee, the male attaches himself to the back of the female's shell by gripping her top himself to the back of the female's shell by gripping her top shell with claws in his front flippers. He then folds his shell with claws in his front flippers. He then folds his long tail under her shell to mate. long tail under her shell to mate. On the nesting beach after recently mating, females can often On the nesting beach after recently mating, females can often be seen having scratched shells and may be bleeding from be seen having scratched shells and may be bleeding from where the males' were hooked to their shells.where the males' were hooked to their shells.Copulation can take place either on the surface or under Copulation can take place either on the surface or under water. Sometimes many males will compete for females and may water. Sometimes many males will compete for females and may even fight each other. When fighting both males and female even fight each other. When fighting both males and female can show very aggressive behavior. Females may mate with can show very aggressive behavior. Females may mate with several males just prior to nesting season and store the several males just prior to nesting season and store the sperm for several months. When she finally lays her eggs, sperm for several months. When she finally lays her eggs, they will have been fertilized by a variety of males. they will have been fertilized by a variety of males.

NESTING & EMERGENCE…NESTING & EMERGENCE…• Although sea turtles move swiftly in the ocean, they are slow and Although sea turtles move swiftly in the ocean, they are slow and

defenseless on land. Female sea turtles leave the ocean only to lay defenseless on land. Female sea turtles leave the ocean only to lay eggs and, for most species, nest only at night. A female may nest eggs and, for most species, nest only at night. A female may nest every 2-3 years. Nesting can take between 1-3 hours.every 2-3 years. Nesting can take between 1-3 hours.

• After a female turtle drags herself up the beach, she hollows out a After a female turtle drags herself up the beach, she hollows out a pit with her back legs and deposits from 50-200 eggs the size of pit with her back legs and deposits from 50-200 eggs the size of golf balls.golf balls.

• When the last egg is laid, the turtle covers the eggs with sand, When the last egg is laid, the turtle covers the eggs with sand, taps down the sand and flings more sand about with her flippers to taps down the sand and flings more sand about with her flippers to erase any signs of the nest.erase any signs of the nest.

• After about two months, the hatchling turtles emerge at night. The After about two months, the hatchling turtles emerge at night. The light reflected off the water from the sky guides them to the sea. light reflected off the water from the sky guides them to the sea. These days, car headlights, street lamps, or lights on buildings These days, car headlights, street lamps, or lights on buildings near the beach cause some hatchlings to travel in the wrong near the beach cause some hatchlings to travel in the wrong direction.direction.

• Any babies still on the beach in the morning are easily picked by Any babies still on the beach in the morning are easily picked by predators or die in the hot sun. It is thought that when the predators or die in the hot sun. It is thought that when the surviving hatchlings reach maturity, they return to the beach where surviving hatchlings reach maturity, they return to the beach where they hatched to lay their eggs.they hatched to lay their eggs.

• Australian Flatback turtle:6-9 weeksAustralian Flatback turtle:6-9 weeks• Green sea turtle: 7-10 weeks.Green sea turtle: 7-10 weeks.• Hawksbill turtle: 60 days (average)Hawksbill turtle: 60 days (average)• Kemp’s Ridley turtle: 6-10 weeksKemp’s Ridley turtle: 6-10 weeks• Leatherback turtle: 55 to 75 daysLeatherback turtle: 55 to 75 days• Logger head turtle: Logger head turtle: 46 to 80 days46 to 80 days• Olive Ridley turtle: approximately 45 daysOlive Ridley turtle: approximately 45 days

Sea Turtles produce large numbers of offspring and Sea Turtles produce large numbers of offspring and give little to no parental care, leaving the give little to no parental care, leaving the offspring to compete for their own resources and offspring to compete for their own resources and survival. Death is very high among offspring, but survival. Death is very high among offspring, but those that do reach adulthood have a good chance of those that do reach adulthood have a good chance of surviving to old age. This type of survivorship is surviving to old age. This type of survivorship is demonstrated by sea turtles, as well as most species demonstrated by sea turtles, as well as most species of plants, invertebrates and fishes.of plants, invertebrates and fishes.

GESTATION & PARENTAL CARE*GESTATION & PARENTAL CARE*

MALEMALESEA TURTLE SEA TURTLE

REPRODUCTIVE REPRODUCTIVE ORGANSORGANS

FEMALE SEA FEMALE SEA TURTLE TURTLE

REPRODUCTIVE REPRODUCTIVE ORGANSORGANS

Most females sea turtles return to the beach Most females sea turtles return to the beach where they were first hatched and often where they were first hatched and often travelling hundreds of kilometres to do so. travelling hundreds of kilometres to do so. Because their bodies are well developed to a life Because their bodies are well developed to a life in the sea, sea turtles move slowly and with in the sea, sea turtles move slowly and with difficulty on land, dragging themselves up the difficulty on land, dragging themselves up the beach to find a spot to dig a hole. The females beach to find a spot to dig a hole. The females each lay several hundred eggs that look a bit each lay several hundred eggs that look a bit like ping pong balls, then fill in the hole and like ping pong balls, then fill in the hole and return to the sea. When the eggs hatch, the tiny return to the sea. When the eggs hatch, the tiny hatchlings dig out of the sand and dash for the hatchlings dig out of the sand and dash for the sea. There are many birds, crabs and animals sea. There are many birds, crabs and animals waiting to grab them as they make their way to waiting to grab them as they make their way to the sea, where other predators are waiting also. the sea, where other predators are waiting also. Only about 1% of all hatchlings reach adulthood. Only about 1% of all hatchlings reach adulthood. If the offspring are able to reach the ocean, If the offspring are able to reach the ocean, they are likely to live and this life cycle they are likely to live and this life cycle continues. continues.

INTERNAL ANATOMY & SKELETON INTERNAL ANATOMY & SKELETON OF A TURTLE OF A TURTLE

(A) Plastron (A) Plastron

(B) Carapace, showing the (B) Carapace, showing the relationship between bony relationship between bony and horny parts of the and horny parts of the shell of a freshwater shell of a freshwater turtle. Shaded areas turtle. Shaded areas indicate parts of horny indicate parts of horny shell; dark lines indicate shell; dark lines indicate joints in underlying bone. joints in underlying bone.

(C) Relationship (C) Relationship between the dermal between the dermal bones (plastron and bones (plastron and carapace) and the carapace) and the axial skeleton in a axial skeleton in a marine turtle.marine turtle.

SIDE VIEW OF A SEA SIDE VIEW OF A SEA TURTLE SKELETONTURTLE SKELETON

The turtle’s shell is an adaptation that protects it The turtle’s shell is an adaptation that protects it from predators. The carapace and plastron each arose from predators. The carapace and plastron each arose from two types of bone: dermal bones that form in the from two types of bone: dermal bones that form in the skin and endochondral bone derived from the skeleton. skin and endochondral bone derived from the skeleton. The carapace consists of 10 trunk vertebrae and their The carapace consists of 10 trunk vertebrae and their ribs, which are overlain by and fused to dermal ribs, which are overlain by and fused to dermal plates. plates.

TURTLE SHELLTURTLE SHELL

Another series of dermal plates Another series of dermal plates forms the perimeter of the forms the perimeter of the carapace. The plastron usually carapace. The plastron usually contains four pairs of large plates contains four pairs of large plates and a single one centered near the and a single one centered near the front (the anteromedial plate); front (the anteromedial plate); these plates are large dermal these plates are large dermal bones, although the anterior ones bones, although the anterior ones may contain parts of the shoulder may contain parts of the shoulder girdle. The shell is modified and girdle. The shell is modified and shaped to meet the needs of shaped to meet the needs of defense, feeding, and movement.defense, feeding, and movement.

• The largest leatherback recorded was 916 kgThe largest leatherback recorded was 916 kg• An interesting fact about incubation is that if An interesting fact about incubation is that if

the sand if warmer, 35 C or higher, the eggs will the sand if warmer, 35 C or higher, the eggs will be female. If it is cooler 28 C and lower they be female. If it is cooler 28 C and lower they will be malewill be male

• Most Sea Turtles are nomads and travel about Most Sea Turtles are nomads and travel about 1,300 miles a day! Leatherback Sea Turtles have 1,300 miles a day! Leatherback Sea Turtles have the longest migration of all Sea Turtles. the longest migration of all Sea Turtles.

• In 1947, 92,000 Sea Turtle nests were estimated. In 1947, 92,000 Sea Turtle nests were estimated. Since then the number of nests has been going Since then the number of nests has been going down. down.

• On a Sea Turtle's shell there are strange On a Sea Turtle's shell there are strange markings. A lost culture has believed they could markings. A lost culture has believed they could tell when the end of the world could be by tell when the end of the world could be by reading the marks. reading the marks.

OTHER FACTS?OTHER FACTS?

BY: ANNIE BY: ANNIE

TRANTRAN