Sea Turtles An Ecological Guide

Sea turtles and breathing

- All sea turtles have multi-chambered lungs full of spongy and elastic tissue providing large amounts of surface area for oxygen and carbon dioxide exchange; this allows sea turtles to exchange oxygen at a faster rate than any other reptile. - Sea turtles also have a strongly reinforced airway which is thought to help prevent airway collapse from the increased pressures encountered during deep diving. - Sea turtles breathe by moving their pectoral and pelvic muscles (think of flapping your arms and legs), which compresses the area containing the lungs and changes the pressure within the lung cavity allowing both inhalation and exhalation to occur. - Shallow diving, air-breathing organisms usually inhale before a dive and store most of the oxygen for that dive within their lungs. In contrast, the leatherback sea turtle is adapted to store much of the oxygen it needs for deep diving within its blood and other tissues. This has the advantage of making oxygen more quickly available to the body cells and keeping it available even after lung collapse associated with a deep dive would normally have cut off those oxygen stores.

Loggerhead sea turtle

- Caretta caretta - western atlantic adults average 250 lbs, mediterranean adults rarely exceed 200 lbs - average adult carapace length ranges from 30 to 42 inches - relatively large head and powerful jaw muscles enable this turtle to effectively feed on hard-shelled prey - carapace is slightly heart-shaped, and the scutes do not overlap - the nuchal scute is in direct contact with the first costl scute on each side - carapace color is reddish brown, while the plastron is generally a creamy yellow color - relatively slow swimmer, thicker posterior portion of the carapace - each limb has two claws This animal is named for its proportionally large head and powerful jaws. The upper shell (carapace) is brown and reddish-brown. The body skin ranges from brown to yellow. The lower shell (plastron) ranges from creamy to yellow. The scales on the top of the head are often a deep rusty brown color. Adults of this species weigh from 170-500 pounds (77-227 kilograms) and are nearly four feet (1.2 meters) in total length. Size: four feet (1.2 meters) Weight: 170-500 pounds (77-227 kilograms) Diet: carnivorous and feeds on a variety of crabs, jellyfish, shellfish and sponges Lifespan in wild: more than 50 years

Leatherback sea turtle

- Dermochelys coriacea - largest of all turtles - males can exceed 9 ft in length and weigh 2000 lbs or more - lifespan around 45 years - carapace color ranges from black to dark brown, often with pink, white, or bluish splotches - plastron is whitish - carapace has seven narrow ridges running its entire length, with six longitudinal ridges found on the plastron. Scientists believe the ridges improve laminar flow and promote swimming efficiency - unlike other sea turtles, leatherbacks lack a hard shell; the carapace is composed of small osteodermic pieces (think tiny little bones) embedded in a thick matrix of cartilaginous dermal tissue; as such, there are no scutes on the shell - critically endangered - mostly eat jellyfish and salps - primarily solitary (though they may gather in small groups in areas where their prey are concentrated) - no claws on its limbs

Leatherback distribution

- Found worldwide in all oceans - They've even been found in the Barents Sea, making them the most northern-occurring reptile in the world - Leatherbacks have even been seen swimming amongst ice!

Anatomy of a sea turtle - cloaca

- Located beneath the tail - The cloaca forms an interior space where both reproductive and excretory products empty, internal fertilization occurs and even in some cases, urinary nitrogen is held for later digestive use

Anatomy of a sea turtle - osmoregulatory system

- Salt gland and kidney - Controls salt and water balance

Anatomy of a sea turtle - scute

- Single keratinous scales overlaying the bony carapace - The number and arrangement of the scutes helps to identify one species of sea turtle from another

Anatomy of a sea turtle - carapace

- The dorsal, or upper side, of the shell - In all but the leatherback, the backbone and ribs are fused to form the carapace

What do sea turtles eat?

- Very young juveniles who live among flotsam in open ocean drift lines feed on a variety of zooplankton, holoplankton, crustaceans, and other invertebrates - Green sea: finely serrated beaks --> variety of sea grasses (preferably newer growth). They have a specialized hindgut with microbial fermentation to digest plant material --> high amounts of released energy in the plant cells - Hawksbill: narrow, protruding beak --> prey lodged in cracks and crevices in the reef, most often sponges --> so they consume spicules (like little shards of glass) and toxins - Leatherback: pointed cusps and sharp-edged jaws --> grabbing and ripping apart siphonophores, jellies, etc. Backward-pointing flexible spines in their mouths and throats help swallow the chomped-up gelatinous tidbits and direct them into the turtle's stomach. - Loggerhead: jaws designed for crushing and grinding --> primarily molluscs and crustaceans, but they're omnivores - Olive ridley: crustaceans, molluscs, gastropods, jellyfish, salps, fish, fish eggs, algae, etc. - Kemp's ridley: primarily crabs - Flatback: primarily soft-bodied benthic invertebrates, including sea cucumbers, soft corals, and sea pens

Human-associated stresses

- artificial lighting - beach/coastal alteration (beach enrichment/nourishment, seawall construction or armoring, coastal development, beach cleaning machines, tourism and beach use, cars driving over sand compacting it, nearshore dredging - boating (vessel strikes, propellors, etc.) - *** fishing (trawling, longline fishing, driftnets, lobster and fish trap lines, and gillnets --> death by drowning, injury, etc.) (discarded or lost fishing gear, ingestion of fishing hooks) (discarded bycatch --> attracts turtles to high-traffic areas) - introduced/invasive species - marine debris (ingestion & entanglement) - pollution (oil spills, other contaminants like heavy metals and PCBs, nutrients and algal blooms) - harvesting sea turtles (food, jewelry, aphrodisiac, etc.) - tourism (coastal development, recreational beach use, imprinting on divers and humans who feed them, etc.)

population status of leatherbacks

- been around before the age of dinosaurs, but critically endangered today - some of the largest nesting assemblages have virtually collapsed in recent years - ex: the nesting population in Malaysia represents 1% of what it was in the 1950s, due largely to decades of unregulated egg harvest - the Pacific coast of Mexico, until recently the species' largest nesting colony, is today less than 10% of what it was just a decade ago, due largely to the incidental capture and mortality of sub-adults and adults in fishing gear on foraging grounds far distant from the nesting beaches (note: this source is from 2004)

leatherback ecology

- can dive deeper than 3900 ft (1200 m) - such deep diving may be possible in part due to a flexible carapace and plastron (made of cartilage embedded with mini bones) - additionally, deep diving may be facilitated by the ability of both the leatherback's blood and muscle tissue to hold high amounts of oxygen (rather than storing oxygen in the lungs), because during deep dives the lungs would be strongly compressed by the increased water pressure - primarily pelagic, the leather back has the widest range of any sea turtle and tolerates cold water due to thermoregulatory adaptations (counter-current heat exchange systems in the circulatory apparatus in their limbs, high oil content, and large body size)

Predation avoidance strategies

- crypsis (coloration, like light plastron, dark shell) - escape behavior (most sea turtles can produce short bursts of speed from their powerful foreflippers - structural deterrents (hard carapace) - chemical deterrents (Hawksbills & diet) - behavioral deterrents (sleeping in holes: greens and hawksbills are known to sleep wedged in holes and over-hangs amongst the reefs. Some turtles may turn sideways and present a bony shield to potential predators, others may dive deeply, others may become aggressive and attempt to bite potential predators)

primary threats to sea turtles

- fisheries - habitat modification - egg harvesting - feral animals - artificial lighting

Seven species of sea turtles

- green sea turtle: commonly thought to have been named for the greenish tinge of its internal fat, which may absorb pigments from the plants the turtle consumes - hawksbill sea turtle: name for the shape of its head and beak - leatherback sea turtle: named for its tough rubber-like skin and lack of a fused bony shell - loggerhead sea turtle: named for its relatively massive, block-like head - kemp's ridley sea turtle: named after Richard Kemp, who discovered the species - olive ridley sea turtle: named perhaps for the olive-green color of its shell. Lepidochelys comes from a Green root meaning "scaly"; the olive-ridley has the greatest number of "shell scales" (scutes) of any of the sea turtles - flatback sea turtle

Predators on sea turtles

- highest predation rates for sea turtles (like most marine organisms) occur during the egg, hatchling, and young juvenile stages - ants, crabs, raccoons, foxes, coyotes, vultures, and other scavenging predators, bad bacterial conditions in the nest, seabirds, reef and pelagic fish such as groupers, jacks, snappers, and eels - as adults, sea turtles have very few natural predators other than orca whales and a variety of sharks

Green sea turtles & seagrass

- keystone species that determine whether seagrass environments are detrivore or herbivore dominated communities - biochemically, younger seagrass blades are easier to digest and high in nutritional nitrogen (requied for protein synthesis in herbivores), while older blades contain more hard-to-digest structural materials like lignin. - through selective grazing, green sea turtles maintain grazing plots full of young blades, which benefits the entire community - lack of cropping --> ungrazed blades lead to fewer and larger plants --> overall less biomass of seagrass --> Old, decrepit plants slowly breakdown in a detrital environment - cropping --> "Grazing plot": fresh young leaves with higher nutritional content; more leaves and higher biomass --> over time, grazed plots contribute importantly to coastal processes (stabilizing sediments, recycling nutrients) and offer food and shelter to a healthy array of smaller herbivores --> herbivore-dominated seagrass community

Hawksbill & sponges

- keystone species that determines species biodiversity of sponges - Caribbean hawksbills feed selectively on only a few orders of sponges (Astrophorida, Hadromerida, Spirophorida) --> this high selectivity may result in rarer species becoming established and competing successfully for space and nutrients on the reef

Comparative sizes of sea turtles

- leatherback 12 ft - green sea turtle 4 ft - loggerhead 3.8 ft - hawksbill 3.2 ft - olive ridley 2.8 ft

Leatherback nesting

- nesting sites tend to be located on isolated beaches adjacent to deep water - females mate every two to three (or more) years and can nest as often to 12 times during a reproductive year - the comparatively large eggs are about 2" in diameter - Like most sea turtles, it is a nocturnal nester. It is also the most marine of all the sea turtles and has great difficulty hauling ashore to nest. Like other species of sea turtles, the leatherback is unable to back up. If it cannot push through beach debris, it will overheat and die in the heat of the sun the following day. New World nesting occurs primarily during the month of December. Most females nest each year and produce six to seven clutches at 10 day intervals. In Pacific Mexico, the average is three nests per female with a clutch size of 50. However, in other areas, clutch sizes from 100 to 180 eggs are recorded. The incubation period varies between 50 to 55 days.

Loggerhead nesting

- one of the largest nesting grounds in the world is in Florida - tends to occur between March and June - females can nest 3 to 5 times or more in a single nesting season - another nesting area is Masirah Island off of Oman - considered endangered globally, and threatened in the US

Sea turtles and sea water

- sea turtles are hypo-osmotic compared to sea water, meaning they lose water to the surrounding ocean - their skin and shell are highly resistant to water diffusion, which helps, and they drink sea water - sea turtles have special salt glands (similar to tear ducts) located near their eyes, which constantly pump excess salt out of the body in thick "tears"

Sea turtles and vision

- sea turtles are thought to be near sighted above water - loggerhead and green sea turtles can see all colors - however, they see orange the best!

Sea turtles and metabolism

- sea turtles have an adjustable metabolism which assists them in staying underwater for long periods of time - green turtles can stay underwater for up to 5 hours - hawksbills can stay underwater for up to 45 minutes

When did sea turtles first appear?

- sea turtles originated in the lower Mesozoic Era - the oldest fossil dates back some 112 million years ago to the middle Cretaceous period - turtles first appeared on land 200 million years ago - by the late Cretaceous, four distinct sea turtle families roamed the sea, but only two of these families have made it to today

Sea turtles and other senses

- they can sense the direction of the earth's magnetic field and also distinguish among magnetic fields characteristic of different geographic areas - substance called magnetite in their brains?

Sea turtles and hearing

- they have no external ears, their ear canals are covered by skin - they are sensitive to low frequency sound up to 1000 hz

Arribadas

- unique nesting event to KR and OR - Spanish term for "arrival" - KR nesting is concentrated near the small town of Rancho Nuevo, Mexico. - on June 18, 1947, an estimated 42,000 KR were observed nesting on a single beach on a single day - in contrast, fewer than 300 females nested per year during the entire 1980s - the decline is attributed to intensive harvesting of eggs and the mortality of juveniles and adults in trawl fisheries - the nesting beach at Rancho Nuevo has been protected by the Mexican government since 1966. This, coupled with strict regulations governing the use of "turtle excluder devices" (TEDs) in shrimp trawls plying the Gulf of Mexico, has resulted in bringing this species back from the brink of extinction - roughly 5,000 US shrimp trawlers in the Gulf of Mexico in 1947 vs. about 55,000 in 1989

What characterstics do all reptiles share?

- vertebral column (spinal column) (aka they are part of the vertebrates) - epidermal scales (which serve to protect the underlying muscles and other internal organs and reduce water loss) - Air breathing (reptiles respire through their lungs, do not have gills like fish) - Ectothermic (cold-blooded) (hence basking) - internal fertilization (sperm in eggs in the female) - All sea turtles lay eggs

how do hatchlings navigate from the nest to the open ocean?

- visual orientation: eyes & subtle brightness of ocean - wave orientation - magnetic orientation: magnetite in brains

The pineal gland

?

Chelonitoxin

A form of poisoning that occurs from humans eating sea turtles. Perhaps in the case of the hawksbill it results form toxins associated with the sponges that the turtle feeds on, toxins that bioaccumulate in the tissues. Effects from consuming hawksbill meat include headaches, severe stomach pain, nausea, vomiting, rapid heartbeat, pale skin, sweating, dizziness, difficulty in swallowing, skin rash, and a burning sensation around the mouth, lips, and tongue. In severe cases, even death can occur.

Flatback Sea Turtle Nesting

According to Limpus et al. (1988), the flatback nests up to 4 times per season at 13 to 18 day intervals. The flatbacks lay relatively small clutches of eggs (average 50). The nesting season in Queensland Northern Territory is from October - February, but it may nest year-around in Northwestern Australia.

Pacific Black Sea Turtle (aka East Pacific Green Sea Turtle) Description

Adult Pacific black sea turtles have an almost black coloration to the carapace. The carapace is dramatically tear-drop shaped at the posterior. The plastron is generally dark gray or gray-green. Adult black turtles weigh as much as 220 pounds (100 kilograms) and measure up to 39 inches (100 centimeters) in carapace length. Hatchling Pacific blacks have a black carapace and white plastron. Hatchlings also have white marginal coloration. Some experts do not distinguish between the Atlantic green and Pacific black as separate species. At Sea Turtle, Inc. we consider them two different species. Physical similarities between the Atlantic greens and Pacific blacks include one pair of prefrontal scales on the head. Also, both have 4 costal scutes (along the spinal column). The head size of the Pacific black is comparatively smaller than that of Atlantic green sea turtles.

Atlantic Green Sea Turtle Description

Adult green sea turtles grow to a length of four feet (1.3 meters) and range from 250 to 450 pounds (113-204 kilograms). Conant (1991) lists a record size of over 650 pounds (295 + kilograms). The adult's shell ranges from a rusty reddish brown to light brown with darker mottling. The most distinctive identifying character of the green turtle are the two large oblong preocular scales between their eyes. The green turtle is named for the color of its fat, not for its overall coloration.

Pacific Black Sea Turtle current threats and historical reasons for decline

Although this turtle enjoys a protected status in the Galapagos Islands, some portions of this population nest in coastal Ecuador where they are being exploited. In Mexico, despite laws to protect them, the turtles continue to be captured and sold by local Nahuatal people on the black market. According to Alvarado and Figueroa (1986) offshore poaching with shark gill nets and incidental capture in shrimp trawls are the main factors contributing to this species decline. In the 1960s, turtle hide hunting intensified in Mexico as a result of a ban on the export of crocodile skins to the international markers. The black turtle is known to hibernate in the Northern Gulf of California where it is consumed by the indigenous Seri India population.

Sexual dimorphism

As adults, males and females can be distinguished by the difference in tail length; adult males have characteristically long tails, curved claws on the flippers, and often a slight concave plastron. All of these features assist the male during mating. Immature turtles can not be sexed based on external characteristics.

Identifying turtle tracks

Average width of turtle tracks symmetrical: - black 70-90 cm - flatback 90 cm - green 100-130 cm - leatherback 150-230+ cm asymmetrical: - Kemp's ridley 70-80 cm - Olive ridley 70-80 cm - hawksbill 70-85 cm - loggerhead 80-90+ cm

Easy guide to sea turtle identification

Back cover

Atlantic Green Sea Turtle current threats and historical reasons for decline

Commercial canneries in Florida and Texas in the early 1900s took a heavy toll. Green turtle soup is a delicacy in most areas where the turtle is found. Ship manifests from the 1800s and before reveal a thriving trade in green turtles in the area of the mouth of the Rio Grande River (Rio Bravo) of Texas/Mexico.

Anatomy of a sea turtle - front vs. back flippers

Front flippers - functions as both a wing (lift) and a propeller (thrust) Back flippers - function as rudders for steering, and nest digging

Turtles as FADs

Given their habit of floating mostly motionless for long periods of time on the surface, sea turtles can function as Fish Aggregating Devices (FADs) (and sometimes for seabirds too) Advantages: small fish gain protection Disadvantages: aggregations of species tend to attract the interest of predators that would not normally bother sea turtles (ex: accidentally impaled on a swordfish)

The role of sea turtles as a keystone species

Green sea turtles --> seagrass productivity & abundance Hawksbill --> competing sponges Leatherbacks --> jellyfish abundance & accidental bycatch --> cascade effect within the ecological community

Atlantic Green Sea Turtle Habitat and Distribution

Green sea turtles are generally found in shallow waters along reefs, in bays and estuaries. They are found throughout the world, predominantly in tropical and subtropical waters. On occasion isolated nesting may occur on the Texas coast. Freezing weather in 1983, 1984, 1989, and 2011 stunned a large number of juvenile green turtles in the Laguna Madre of South Texas. A nesting population of yet undetermined size exists between La Pesca and Tampico, in the State of Tamaulipas, Mexico.

Hawksbill Sea Turtle Habitat and Distribution

Hawksbills are denizens of coral reefs and rocky areas, shallow costal areas and lagoons. They are found worldwide in tropical and subtropical seas. Specimens sometimes wash ashore dead or entangled in fishing nets, lines, or onion bags along the Texas Coast. A sizable nesting population exists on coasts of Campeche and Yucatan, Mexico.

Kemp's Ridley Current Threats and Historic Reasons for Decline

Large scaled exploitation of eggs and meat at the main nesting beach occurred from the 1940s through 1960s. In the early 1970's the Mexican and Texas governments joined forces to protect the remaining stock. Current threats include incidental drowning from entanglement and poor fishing practices. Future threats could be the development of key nesting beaches for the Kemp's ridley.

Feeding adaptations

Leatherback - piercing Green sea - scraping Hawksbill - cutting Loggerhead - crushing

Loggerhead habitat and distribution

Loggerhead sea turtles inhabit estuaries, lagoons, bays and ship channels in warm and temperate seas and oceans worldwide. Known nesting grounds for this species are located in the wider Caribbean, Southeastern United States, the Yucatan in Mexico, Belize, Guatemala, Nicaragua, Panama, Columbia, Venezuela, Puerto Rico, the Dominican Republic, Jamaica, Cuba, Brazil, Laganas and Kalimaki in Greece and in Dalyan beach in Turkey. Habitat: estuaries, lagoons, bays and ship channels Range: All but the most frigid oceans. Prefer coastal water, but have been found inland in rivers. Migration: Can sometimes travel thousands of miles to return to nesting grounds

Current threats and historical reasons for leatherback decline

Longline fishing is the biggest threat to Leatherback populations. The type of hooks currently used, called "J Hooks" are accidentally catching and subsequently drowning thousands of leatherbacks. A new hook called a "Circle Hook" is currently being tested and implemented within many of the longline fisheries. This new style of hook catches tuna and swordfish (the desired catch) but not sea turtles. Other major threats to leatherback populations are the accidental consumption or entanglement with plastics and discarded nets and line. Historically, the seasonal harvest of millions of eggs and the slaughter of thousands of nesting turtles has brought this species to its endangered status.

The range of salt glands in marine reptiles

Marine iguana: sneezes - modified nasal glands in the nose Sea turtle: cries - modified lachrymal glands in the eyes Sea snakes: salivates - modified salivary glands in the mouth Saltwater crocodile: drools - modified lingual glands in the mouth Fun fact: the leatherback's salt gland is more than TWICE the size of its brain - highlighting the importance of this organ!

Types of sea turtle symbiosis

Mutualism (benefits both) - ex: cleaning stations Commensalism (benefits other animal, turtle is indifferent) - ex: ramoras, barnacles, copepods Parasitism (benefits other animal, hurts turtle) - ex: barnacles, trematodes & flukes, nematodes, leeches, mites

Kemp's Ridley Sea Turtle Distribution

Nearly the entire nesting population comes ashore near the community of Rancho Nuevo, Tamaulipas, Mexico. Occasionally, females nest on the Texas Coast and farther south in the Mexican state of Veracruz. Juveniles are encountered in bays and estuaries as far north as Louisiana and other Gulf states on both sides of the border. Rare specimens have been found as far north as Cape Cod, Massachusetts. However, the majority of the population feeds and nests in the Gulf of Mexico and adults are generally restricted to the Gulf of Mexico. There is not a clear consensus as to whether or not large nesting aggregations of Kemp's ridleys historically occurred on the Texas Coast. Habitat: shallow coastal areas, bays and lagoons Range: Atlantic Ocean and Gulf of Mexico Migration: Travels from the Gulf of Mexico to the New England area, rarely travels across Atlantic. Dive depth: Unknown. The prefer neritic habitat (which means near shore) and typically do not dive very deep.

Unique Traits of the Pacific Black Sea Turtle (aka East Pacific Green Sea Turtle)

Pacific black sea turtles are well known for presenting a basking behavior along the Hawaiian islands, particularly the French Frigate Shoals. These sea turtles will crawl out of the shallow water and lay along the rocks and sand in the bright sunlight. This is not a common sea turtle behavior. Scientists do not agree on the reason for the basking - some think that this unique basking behavior has something to do with temperature regulation, or it may be a way for them to rest without fear or predation. Many species of reptiles bask on a regular basis to regulate body temperature. This behavior has created a new eco-tourism niche for the Hawaiian islands. Volunteers are trained to spot and protect the sun bathing sea turtles. Tourists are encouraged to respect the space of the sea turtles and enjoy an odd behavior which allows for close up viewing of these usually aquatic animals.

Pacific Black Sea Turtle (aka East Pacific Green Sea Turtle) General Information

Present population estimates vary from 5,000 to 10,000 individuals. This turtle feeds primarily on marine algae. Pacific blacks primarily nest at night. A typical clutch is 70-100+ eggs. Nesting intervals range from 12-14 days. The eggs typically incubate from 50 to 55 days prior to hatching. Nest sites are usually on wide beaches in coves surrounded by rocky granite cliffs. The nesting process takes between 1-3 hours. This includes emerging from the water, selecting a site, digging, egg laying and covering the eggs with sand. Both black and green sea turtles may dig several nests before laying a clutch of eggs. Sexual maturity is probably attained between 16-30 years of age in this species. Studies conducted in Michoacan on the nests of black sea turtles reveal that nest temperatures below 27.1°C (81°F) produced 0 percent females while temperatures of 31°C (88°F) or higher produced only females. Temperature-dependent sex determination (Bull,1980) is comparatively well defined in many sea turtle populations today.

What class are sea turtles in

Reptilia fun fact: from the latin word meaning "to creep"

Loggerhead general information

Sexual maturity is reached somewhere between 15 to 20 years of age. Like most species of sea turtles, adult males differ in appearance from females in having a much larger and stronger tail. The pair breeds at sea and the female comes ashore to nest. In the U.S., loggerheads nest during the months of April to July. Generally, 105 to 120 eggs are laid per clutch. A single female may lay several clutches per season. Some nest every year, others nest in alternate years. Egg incubation ranges from 55 to 60 days. Like most sea turtles, it nests at night. This species is primarily carnivorous and feeds on a variety of crabs, jellyfish, shellfish and sponges. Some loggerheads bury themselves in the mud during the winter months. Dredges excavating ship channels frequently injure or kill the dormant turtles. Sexual maturity: between 15 to 20 years of age Primary nesting locations: Caribbean, Southeastern United States, the Yucatan in Mexico, Belize, Guatemala, Nicaragua, Panama, Columbia, Venezuela, Puerto Rico, the Dominican Republic, Jamaica, Cuba, Brazil, Laganas and Kalimaki in Greece and in Dalyan beach in Turkey. Nesting season: April to July in the U.S. Nest size: 105 to 120 eggs Nesting time: at night Egg incubation: 55 to 60 days

Olive Ridley's Sea Turtle Nesting

Sexual maturity: around 15 years Primary nesting locations: eastern Pacific and northern Indian oceans, in the countries of: Mexico, Nicaragua, Costa Rica, Panama, India Nesting season: June through December Nest size: 110 eggs Nesting time: Also nests in an "arribadas," during the night Egg incubation: 52 to 58 day

Atlantic Green Sea Turtle

Species name: Atlantic green sea turtle Nombre en Español: Tortuga Blanca, Tortuga Verde Latin Name: Chelonia mydas Family: Cheloniidae IUCN Endangered Status: Endangered Green sea turtles are known to migrate long distances (up to 1,400 miles) between feeding grounds and nesting beaches. This turtle is mostly herbivorous, feeding on a variety of sea grasses and marine algae including: Thalassia, Zostera, Cymodocea and Halophila. Depending on the size of the female, they lay from 75 to 150 eggs per clutch. Some females have been recorded laying as many as seven clutches in a season. The eggs incubate for 48 to 70 days. Like most sea turtle species, green sea turtles nest at night. Individual turtles only nest every 2, 3 or 4 years. In the Gulf of Mexico at Rancho Nuevo, green sea turtles begin nesting in June and continue through October.

Flatback Sea Turtle

Species name: Flatback sea turtle Nombre en Español: Tortuga Franca Oriental Latin Name: Natator depressus Family: Cheloniidae IUCN Endangered Status: Unknown (data deficient) The Latin species name "depressa" means flat. This name refers to the flatness of this sea turtle's carapace. As adults, the flatback has a yellow-grey or a green-grey colored oval shaped carapace. The plastron is typically a pale yellow. There is a yellow band underneath and outlining the marginal scutes. Adults may weigh as much as 198 pounds (90 kilograms) and measure 39 inches (100 centimeters) long. There is a single pair of prefrontal scales on the head. The carapace has four pairs of costal scutes. The head is relatively larger than that of a comparable sized green turtle and is more triangular in shape. Similar to the Leatherback sea turtle (Dermochelys coriacea), the flatbacks have a soft shell. Hatchling flatbacks are a light tannish-grey color with bright black outlines along the carapace scutes. The plastron is white. They also have white-tan fringing along the marginal scutes and flipper edges. At one time, this turtle was considered a relative of the green sea turtle, but it was returned to it's own genus, Natator, by Limpus et al. (1988) and Zangerl and Hendrickson (1988).

Hawksbill Sea Turtle

Species name: Hawksbill sea turtle Nombre en Español: Tortuga Carey Latin Name: Eretmochelys imbricata Family: Cheloniidae IUCN Endangered Status: Critically Endangered

Kemp's Ridley Sea Turtle

Species name: Kemp's ridley sea turtle Nombre en Español: Tortuga Lora Latin Name: Lepidochelys kempii Family: Cheloniidae IUCN Endangered Status: Critically Endangered (The most endangered of all sea turtles)

Olive Ridley Sea Turtle

Species name: Olive Ridley Nombre en Español: Golfina Latin Name: Lepidochelys olivacea Family: Cheloniidae IUCN Endangered Status: Vulnerable (Endangered in Mexico) According to Gotch (1988) this ridley was named after H.N Ridley FRS, who was on the island of Fernando de Noronha, and in Brazil in 1887. As both its common and species names imply, the overall color of this turtle is olive green. Like its sister species, the Kemp's ridley, it is a small sea turtle, usually less than 100 pounds (45 kilograms). The most obvious difference between this turtle and the Kemp's ridley is the number of costal scutes of the upper shell. The olive ridley has 5 to 9 costals and 7 vertebral scutes. Kemp's ridley has 5 costals and 5 vertebrals. Not so long ago, these turtles were called the Pacific and Atlantic ridley respectively, but the discovery of Lepidochelys olivacea off of the Atlantic coast of South America necessitated a name change. This is an omnivorous turtle which feeds on crustaceans, mollusks and tunicates. An average clutch size is over 110 eggs which require a 52 to 58 day incubation period. Size: up to 2.5 feet in length Weight: less than 100 pounds (45 kilograms) Diet: omnivorous turtle which feeds on crustaceans, mollusks and tunicates. Lifespan in wild: 50 years

Pacific Black Sea Turtle (aka East Pacific Green Sea Turtle)

Species name: Pacific black sea turtle Nombre en Español: Tortuga Blanca, Tortuga Verde Latin Name: Chelonia mydas agassizii Family: Cheloniidae IUCN Endangered Status: Endangered

Kemp's Ridley Sea Turtle Description

The Kemp's ridley is the smallest of the eight species of sea turtles. Adults range from 75-100 pounds (34-45 kilograms). In 1880 a Florida fisherman and naturalist named Richard M. Kemp found the first documented specimen of this turtle. To honor his finding the species name became Lepidochelys kempii. The hatchlings of this species are a solid grey black color. As they begin to grow into juveniles the coloration of the plastron (bottom shell) turns to white. The adults are broadly oval or heart shaped and their shells are olive to gray green. The skin color ranges from creamy color to white. The plastron is a creamy or yellow green in color. The preferred habitat for the Kemp's is shallow coastal areas, bays and lagoons. While in these areas they often seek their favorite food, crabs. One consequence of this habitat choice is that entanglement with fishing nets, hooks and other marine debris is quite common. Size: The smallest living sea turtle, can get up to 2 feet in length Weight: can range from 75 to 100 pounds Diet: favorite food is blue crab, but are opportunistic hunters Lifespan in wild: estimated around 45 years

Olive Ridley Sea Turtle Habitat and Distribution

The Olive ridley inhabits tropical and subtropical coastal bays and estuaries. It is very oceanic in the Eastern Pacific and probably elsewhere too. These animals are found in the Pacific and Indian Oceans, and along the Atlantic coast of West Africa and the Atlantic coast of South America. In the Eastern Pacific it occurs from Southern California, USA to Northern Chile. Large nesting aggregations called "arribadas" still occur in Pacific Costa Rica, primarily at Nancite and Ostional and Pacific Mexico at La Escobilla, Oaxaca. According to the Marine Turtle Newsletter (October 1993), an estimated 500,000 nesting females came ashore during a single week in March, 1991 at Gahirmatha Orissa, India. Habitat: tropical and subtropical coastal bays and estuaries. Range: Pacific and Indian Oceans, and along the Atlantic coast of West Africa and the Atlantic coast of South America. In the Eastern Pacific it occurs from Southern California, USA to Northern Chile. Migration: Can migrate hundreds to thousands of miles each year to return to nesting grounds

Flatback Sea Turtle Habitat and Distribution

The flatback sea turtle inhabits coastal coral reefs and grassy shallows of Australia and Indonesia. It feeds primarily on sea cucumbers and crustaceans, and is found primarily in the northern coastal area of Australia and the Gulf of Papua New Guinea. This species nests exclusively in Australia.

Olive Ridley's Sea Turtle Nesting Current Threats and Historic Reasons for Decline

The last large arribada beach in India is threatened with disaster by the development of a major fishing port and a prawn culture facility. In fact, it threatens the entire Bhitarkanika Wildlife Sanctuary where the beach is located. Past large-scale exploitation for meat, eggs, and leather reduced the once large arribadas to dangerously low levels in the Mexican Pacific states of Jalisco, Michoacan, Guerrero and Oaxaca. In June of 1990, Mexico declared total protection for this species as well as the other species of sea turtles inhabiting Mexican waters, but there is still a trade on the black market. In 1993, 350,000 nests were recorded in Escobilla, Oaxaca (Marquez, 1994, pers. comm.). Mexico has recently opened the Mexican Turtle Center at Mazunte, Oaxaca, near the site of a former turtle slaughter house. Hopefully, some of the same individuals who formerly killed turtles will be able to earn a living by protecting them and educating visitors about them. Despite Mexican initiatives to protect the Olive ridley, this same population is still exploited in the black market in Mexico and harvested as it feeds along the Pacific coasts of Nicaragua and Ecuador.

Kemp's Ridley Sea Turtle Nesting

The nesting season for the Kemp's is from April to July. The nesting range is from Galveston, Texas to Tamaulipas, Mexico with an average clutch size of 100 eggs. This species lays the smallest eggs of all the sea turtles. Sea turtles are perfectly round in shape and have a leathery shell. The Kemp's ridley eggs are about the size of a ping pong ball. Nesting females will on average lay two to three clutches per season. The incubation period ranges from 48 to 62 days, depending on air temperature. The temperature within the nest will affect the sex ratio of the nest. Incubation temperatures below 29.5 degrees Celsius (85 degrees Fahrenheit) tend to produce male offspring. Therefore, lower spring incubation temperatures would tend to produce a large proportion of male babies. The Kemp's is the only sea turtle which routinely nests in the daytime. Gale force winds usually precede nesting aggregations which are called "arribadas" in Spanish. The largest recorded nesting "arribada" was captured in a film from 1947 at Rancho Nuevo beach in Tamaulipas, Mexico. In this film it was approximated that 40,000 turtles came ashore to nest. Today such large aggregations do not occur due to the near extinction of this species. From the 1940s-70s poaching of the nesting turtles and their eggs decimated the population. The Kemp's ridley received federal protection in 1977 under the CITES Act. Due to continued efforts by the Mexican and Texas goverments the Kemp's is now on the road to recovery. Sea Turtle, Inc. operates a nest conservation program of 50 miles of South Texas coast protecting the Kemp's ridley nests. To learn more about our nest conservation program, click here. In 2011, a large arribada occured at Rancho Nuevo, Tamaulipas, Mexico (The main nesting beach for this species). It was estimated that during a 2-day time period up to 7,000 Kemp's ridleys came ashore to lay their eggs. Sexual maturity: 10 to 12 years old Primary nesting locations: Nearly the entire nesting population nests near the community of Rancho Nuevo, Tamaulipas, Mexico. About 1 to 2 percent of the remaining population nests on the Texas Coast and farther south in the Mexican state of Veracruz. they do not nest anywhere else. Nesting season: April to July. Nest size: about 100, and a female can lay two to three nests a season Nesting time: the Kemp's is the only sea turtle which routinely nests in the daytime Egg incubation: 48 to 62 days

Unique Traits of the Flatback

The saltwater crocodile (Crocodylus porosus) is a known predator of nesting flatback sea turtles. Crocodiles have been known to actively track down the nesting turtles. This same species of crocodile is also known to consume nesting Olive ridley (Lepidochelys olivacea) at Playa Nancite in Costa Rica. Other nest predators include dingoes and foxes. Although they lay relatively fewer eggs than other sea turtle species, relative to body size, the flatbacks lay the largest eggs of the sea turtles. An average egg for a flatback weighs 2.7 oz (77g) - which is about the same as that of the huge leatherback sea turtle! Due to the large egg size, flatback hatchlings are the largest of all sea turtle species.

Hawksbill Sea Turtle Description

The slender, somewhat flattened profile of the Hawksbill gives it a streamlined appearance. It is the only sea turtle whose costal and vertebral scutes of the upper shell (carapace) overlap the ones behind them, much like a shingled roof. The upper shell has a beautiful rich reddish brown or dark brown mottling. The head is long and narrow compared to that of other kinds of sea turtles and it has a narrow hawk-like beak, for which it was named. Its weight ranges from 95 to 165 pounds (43-75 kilograms).

Anatomy of a sea turtle - plastron

The ventral, or lower side, of the shell. Joined to the carapace by cartilage.

Hawksbill Sea Turtle Current Threats and Historic Reasons for Decline

There has been over-exploitation of Hawksbills for their eggs and for the highly coveted scutes of the shell. Fingernail like material, or scutes, cover the body shell. These beautifully colored scutes are called tortoise shell (bekko or carey), which is highly sought after to make a variety of expensive trinkets including earrings, bracelets, combs, jewelry boxes and even table tops. Most of the bekko originates from Cuba, Haiti, the Dominican Republic and other Caribbean Islands.

Sea turtles and smell

They have an acute sense of smell

Pacific Black Sea Turtle (aka East Pacific Green Sea Turtle) Habitat and Distribution

This turtle is found primarily in coastal waters, bays and estuaries in tropical and subtropical latitudes. Iverson (1992) lists the distribution of this turtle in the eastern Pacific Ocean from southern California, USA to Chile, west to the Galapagos Islands, Hawaii and Papua New Guinea. According to Alvarado and Figueroa (1986) the primary nesting beaches of Mexico include: Colola, Maruata, Mexiquillo, Chimapa, and Motin de Oro.

Current threats and historical reasons for loggerhead decline

Through out much of its U.S. nesting habitat, raccoons are a major egg predator. Lights on coastal highways and housing developments disorient the nocturnal emerging hatchlings of this species, often causing them to move away from the water and be killed by automobiles. Loggerhead hides are highly valued for their rich color and are widely used to make leather products such as boots, wallets, and purses.

Fun fact about pectoral muscles

To provide for propulsion, more than one third of the sea turtle's interior body cavity area is taken up by the pectoral muscles! Contraction of these muscles also assists in bringing about inhalation and exhalation of the lungs.

Anatomy of a sea turtle - circulatory system

Turtles, like most reptiles, have a three-chambered heart where deoxygenated blood returning from the body pools in the right atria (RA), and then empties into the single ventricle (V) where it is pumped into the lungs. After picking up O2 and dropping off CO2, blood returns to the heart, pools in the left atria (LA), and then empties back into the single ventricle (V) where it is then pumped to the rest of the body.

protocooperation

an act of social facilitation where the hatchlings work together to dig toward the surface at once

caruncle

hatchlings use a caruncle, a specialized egg tooth, to help break free of the egg shell the caruncle disappears shortly after hatching

Sea turtle conservation, management efforts, & legislative tools

pg 102 & 108

How do we obtain data on sea turtles over time?

pg 105

Involving the public

pg 109

What you can do

pg 111

Treaties relevant to the conservation of sea turtles

pg 114

Glossary

pg 116

Shrimp trawling and TEDs

pg 92

Effects of marine debris on sea turtles

pg 95

Turtles and oil spills

pg 97

Products from sea turtles

pg 99

What is in Class Reptilia

sea turtles crocodilians snakes lizards dinosaurs fun fact: reptiles were among the first large animals able to live on land

Sea turtles and mating

sea turtles have internal fertilization, a relative rarity amongst the vast majority of marine animals most adult females do not mate every year (except Kemp's ridleys), but males are more likely to do so sea turtles are promiscuous breeders; long copulation periods and multiple partners help ensure viability for many hundreds of eggs to be laid that year

Sex determination

sex is greatly influenced by the temperature of the sand in the nest where the egg lies (global warming might results in skewed sex ratios, decreased hatch success, and/or the loss of sandy beach habitat) major factors affecting clutch temp: beach temp & heat exchange between clutch and beach sea turtles lack sex chromosomes, meaning that whether a hatchling is a boy or a girl is not determined at the time of fertilization (as is the case with humans), but rather during incubation warmer temps --> females cooler temps --> males "Temperature-dependent Sex Determination" (TSD)

hatchlings

the movement caused by breaking free of the egg shell elicits similar movements in adjacent unhatched shells they all dig toward the surface together (protocooperation) when they reach right below the surface, the intense heat of the surface sand if it's daylight essentially immobilizes them and they stop digging until the sun lowers and the sand cools once at the surface, turtles open their eyes for the first time, orient to the horizon, and scurry to the sea

pivotal temperature

the temperature at which an equal number of male and female siblings are produced in a nest (roughly in the 28 to 29 degree Celsius range)