Sea Turtles

1. Sea Turtles
2. Vaquita
3. Killer Whale
Credits and Links

Sea turtles live in almost every ocean throughout the world. Some species migrate long distances to feed, often crossing entire oceans. They nest on tropical and subtropical beaches.

With their streamlined shells and long limbs and flippers, these reptiles are well-suited for swimming.

While some species may briefly rest on remote island shores and all adult females come ashore to lay eggs, usually several times per season every 2 to 5 years, many sea turtle species spend their entire lives at sea.

A sea turtle’s shell – or carapace – ranges in shape from oval to heart-shaped, depending on the species, and each is uniquely covered in an arrangement of bony plates known as scutes. The bottom side of the turtle shell is called the plastron.

A sea turtle cannot retract its limbs, head or neck under its shell like a land turtle. Their hind flippers serve as rudders, helping to stabilize and direct the animal as it swims.

Sea turtles have large upper eyelids that protect their eyes, they do not have an external ear opening and like other turtles, sea turtles lack teeth.

Both male and female sea turtles are equal in size while the male’s tail may extend beyond the hind flippers.

There are 7 Sea Turtles species found across the planet. They each have their own characteristics, appearance and size, preferred habitat range and diets.

Each species relies on a different preferred foods: Green Turtles eat sea grasses, Leatherbacks feed primarily on jellyfish, Loggerheads eat shelled animals such as crabs and clams, Hawksbills feed on sponges and other invertebrates; and the Kemp’s Ridley Sea Turtle seems to prefer crabs.

FLATBACKS

Flatback sea turtles are named after its flat shell, which is unlike the curved shell of other sea turtle species.

They are pale grayish-green in color, grow up to 3 feet long and the can weigh 200 pounds.

They have the smallest distribution of all sea turtle species. Flatbacks breed and nest only in Australia.

The Flatbacks main predator is the Salt Water Crocodile, the largest reptile on the planet.

Their habitat range is generally the coastal waters of Northern Australia and parts of Indonesia. They do not undertake long, open ocean migrations like many other sea turtle species, and Flatbacks are usually found in waters less than 200 feet in depth.

They are omnivores, feeding on a variety of prey including sea cucumbers, jellies, soft corals, shrimp, crabs, mollusks, fish, and seaweed.

GREEN TURTLES

The Green turtle is one of the largest hard-shelled sea turtles. A typical adult is 3 to 4 feet long and weighs 300 to 350 pounds. They have dark brown or black shells and a much lighter, yellow underside. Their shells have five scutes running down the middle and four scutes on each side.

Another distinct characteristic of the green turtle is their two large scales located between the eyes.

They are unique among sea turtles in that they are herbivores, eating mostly seagrasses and algae. This plant-based diet is what gives both their cartilage and fat a greenish color, which is where their name comes from.

They can stay under water for as long as five hours. Their heart rate slows to conserve oxygen, often as slow as 1 heartbeat every nine minutes.

Green turtles live all over the world, nest in over 80 countries, and live in the coastal areas of more than 140 countries.

Adult and juvenile Green turtles are generally found nearshore as well as in bays and lagoons, on reefs, and areas with seagrass beds.

Adults will migrate from foraging areas to nesting beaches and may travel hundreds miles each way. After emerging from the nest, hatchlings swim to offshore areas, where they live for several years. Once the juveniles reach a certain age or size range, they will leave the open ocean habitat and travel to nearshore foraging grounds.

Green Turtles can be found along all coastal shores of the United States but are mostly concentrated in the warmer waters.

The majority of adult green turtles that feed throughout the main Hawaiian Islands migrate to French Frigate Shoals in the Northwest Hawaiian Islands to nest. Green Turtles in the Hawaiian Islands are natively known as “Honu” and have been a part of ancient Polynesian history and lore for centuries.

HAWKSBILL

Hawksbill turtles are found throughout the tropical waters of the Atlantic, Pacific, and Indian Oceans. Their diet consists mainly of sponges that live on coral reefs.

Hawksbills get their name from their unique beak-like mouths. With a head that comes to a point, and a V-shaped lower jaw, they are said to have a hawk-like appearance.

They are small to medium-sized sea turtles – growing up to 3 feet in length. They possess amber-colored and patterned shells with overlapping scutes. The scutes are usually golden brown with streaks of orange, red, and black. The bottom of the shell is a light yellow.

Unique to hawksbill sea turtles is a pair of claws on each flipper. Hawksbills also have four scales between their eyes compared to green turtles with two scales.

Hawksbill turtles are often found near coral reefs which are home to their preferred food—sea sponges. However, in the Eastern Pacific, they are found in mangrove estuaries.

They are omnivorous and even opportunistic feeders who will eat mollusks, marine algae, crustaceans, sea urchins, small fish, and jellyfish.

The shape of their mouth and their sharp beaks enable them to reach into small holes and crevices in coral reefs to find food.

Hawskbills are found in the circumtropical regions of the worlds oceans and they are not found in the Mediterranean Sea.

Hawksbill turtles are endangered because of highly prized and decorative shell. They were hunted for hundreds of years in huge numbers for the “tortoise shell” that was used in many types of jewelry, combs, brushes and trinkets. Harvesting hawksbill turtles for their shell nearly drove the population to extinction.

KEMPS RIDLEY

The Kemp’s Ridley turtle is the smallest marine turtle in the world, measuring only 2 feet long and weighing up to 100 pounds. They are generally grayish-green in color on top with a pale yellowish bottom shell.

They are found primarily in the Gulf of Mexico, but they have also been in the Atlantic Ocean as far north as Nova Scotia.

Kemp’s Ridley turtles are named after Richard M. Kemp, a fisherman from Key West, Florida, who first submitted the species for identification in 1906.

They possess a triangular shaped heads with hooked beaks and strong jaws. They inhabit nearshore habitats where they forage for their favorite prey, crabs.

Kemp’s Ridley turtles are the only marine species that nests primarily during the day. They also nest together in groups similar to their relative the Olive Ridley turtles.

LEATHERBACKS

The leatherback is the largest turtle in the world. They may grow close to 6 feet long and weight nearly 2,000 pounds.

They have a rubbery, primarily black skin with pinkish-white coloring on its underside. Hatchlings possess white dotting marks along the ridges of their backs and flippers.

Their front flippers lack claws and scales and are proportionally longer than in other sea turtles. Their back flippers are paddle-shaped.

They are the most widely distributed sea turtle species and they are highly migratory, some swim over 10,000 miles a year between nesting and foraging sites.

A leatherback turtle is covered with leathery skin, not the plates found on other sea turtles. It is the only sea turtle whose backbone is not attached to the inside of its shell.

It’s tear-drop shaped shell is composed mostly of cartilage raised into seven prominent ridges. A layer of thousands of small dermal bones lies just below the leathery skin. This flexible outer covering helps the leatherback move more effectively in water and they are excellent divers.

With a recorded dive of nearly 4,000 feet – they often dive deeper into the ocean depths than many marine mammals.

Leatherbacks are capable of withstanding the coldest water temperatures often below 40˚F and are found as far south as Chile and as far north as Alaska.

Leatherbacks can consume twice their own body weight in food each day, their diet is primarily jellyfish and other soft-bodied invertebrates. Their mouth and throat have backward-pointing spines that help retain their gelatinous prey.

LOGGERHEADS

Loggerheads reach lengths of 3 to 3 1/2 feet long and weigh up to 400 pounds.

Loggerheads are named for their relatively large head, which support powerful jaws which enables them to feed on hard-shelled prey such as conchs. Loggerheads are carnivores and rarely consume plant material – they eat mostly bottom dwelling invertebrates such as mollusks, horseshoe crabs, and sea urchins.

They can be found in waters throughout the world, second only to the Leatherback in sea turtle distribution.

The loggerhead is the most common sea turtle in the southeastern U.S. They nest primarily along the Atlantic coast of Florida, South Carolina, Georgia, and North Carolina and along the Florida and Alabama coasts in the Gulf of Mexico.

They are the most common species in the Mediterranean, nesting on beaches in Greece, Turkey, and Israel.

Some loggerhead populations nest in Japan and migrate to the coast of the Baja peninsular in Mexico to forage before returning home again.

OLIVE RIDLEY

Olive Ridley sea turtles are the second smallest sea turtles. Their shells grow up to 30 inches and they weigh up to 110 pounds.

The Olive Ridley gets its name from the olive green color of its heart-shaped carapace.

Found primarily in the tropical regions of the Pacific, Indian, and Atlantic Oceans, the Olive Ridley is considered the most abundant sea turtle in the world.

Their shell size, shape and color may also vary among different populations in both the Atlantic and Pacific Oceans. The largest Olive Ridleys are usually found in West Africa.

They are mostly a pelagic species, and are known to dive up to 500 feet to feed on bottom dwelling invertebrates.

Like their relative, the Kemp’s Ridley, Olive Ridleys engage in a behavior known as arribada. Large groups of females gather offshore then come on shore together to nest all at once. This behavior is thought to provide a defense against natural predators.

Though they are the most abundant sea turtle on the planet, the IUCN Red List has noted a reduction in global population up to 50 percent.

An adult female Sea Turtle will typically return to the beach area from which she was originally hatched to lay ping pong ball size eggs in a pit she digs with her hind flippers. She can lay thousands of eggs over her lifetime.

After about sixty days, baby sea turtles (known as “hatchlings”) emerge from their sandy nests and make their way to the ocean. Like most reptiles, the incubating temperature of the eggs determines the sex of the hatchling.

Young sea turtles have many natural predators including birds, crabs, and fish. It is estimated that only one out of 1,000 hatchlings survives to be an adult. The juvenile turtles spend their first few years in the open oceans, eventually moving to protected bays, estuaries, and other nearshore waters as adults.

Tiger Sharks are known for eating sea turtles and some Killer Whales have been known to prey on leatherback turtles but typically they have few natural predators as adults and can live for a several decades.

However, Sea Turtles face many man-made dangers as they travel the seas, including entanglement in fishing gear, the loss of nesting and feeding sites due to over-development of many coastal areas, poaching for the illegal sale of turtle shell products, and ocean pollution including extensive plastic products such as bags which may appear as jellyfish or other edible material to the animals.

Six of the seven species of sea turtles are threatened or endangered. Two are critically endangered, the Hawksbill and Kemp’s Ridley and while not formally listed Internationally yet, the Flatback sea turtle is listed as endangered in Australia.

While it is illegal to trade, purchase or possess sea turtle products, unfortunately a black market still thrives in many places around the world.

The future of the beloved sea creatures does not rest on the work of a select few organizations and and accredited facilities – the future of Sea Turtles and all animal life relies on the efforts of everyone around the globe.

Vaquita

Across the globe there are 90 species of whales, dolphins and porpoises, known collectively as “cetaceans.”

Historically, the name porpoise has been used interchangeably with that of dolphins – most notably the familiar bottle-nosed dolphin – however porpoise and dolphins are two different families and among the 10 families that comprise toothed whales suborder – Odontoceti.

Common distinctions that help mark porpoises include a more rounded head as opposed to the beak-like rostrum of most dolphins, porpoises also possess flat, spatula–like or spade shaped teeth whereas dolphins, including the largest – the killer whale, all possess more pointed, conically shaped teeth.

Typically porpoises are smaller and more stout than their dolphin cousins. Among all of the toothed whale species, one porpoise ranks among the smallest of all, the porpoise known by its Spanish common name – the Vaquita.

The Vaquita, which translates to “little cow” is only found in a very small range of the northern Gulf of California, situated between the Baja peninsula and the mainland of Mexico.

Reaching a length of only 5 feet and weighing between 65 to 120 pounds, Vaquitas have small, strong bodies, they have black patches around their eyes and lips that have lead some to describe them as appearing to wear lipstick and eye-shadow.

Vaquitas also have triangle-shaped dorsal fins in the middle of their backs, which are taller and wider than in other porpoises.

Vaquitas are the only porpoise species adapted to living in warm water. Most porpoises inhabit water that is cooler than 68F but Vaquitas are able to tolerate water that fluctuates from 57 degrees in the winter to 97 degrees in the summer. The larger size of the Vaquita’s dorsal fin is believed to allow the animal’s extra body heat to dissipate.

Though the Vaquita is found in the northern hemisphere, like the harbour porpoise and the Dall’s porpoise, genetic studies have shown that they are more closely related to the spectacled and Burmeister’s porpoises, which both inhabit southern hemisphere regions.

Females are larger than males in total length but adult males have proportionally higher dorsal fins and wider flukes. Mature males may be more agile and swim quicker than females, which some researchers believe may be an advantage during breeding.

Vaquita backs are dark gray, while their bellies are a lighter gray – this dark and light countershading characteristic is found in many dolphin and porpoise species.

Their diet consists of fish, squid and some crustaceans. They spend most of their time under the water and so are not often seen by humans.

Vaquitas often appear alone or in very small groups of 1-3 individuals – usually just a mother and calf. They are rather shy and usually avoid most boats. They go typically unnoticed at the surface as they rarely splash, jump or leap like many of their porpoise and dolphin relatives. This behavior, coupled with their small body size, can make them difficult to observe and study.

Perhaps due to their small size and very limited habitat range, they were not known to the scientific community until 1950 and it the Vaquita wasn’t actually described as a new and rare species of porpoise until 1958.

Vaquitas can live at least 20 years or more. They begin breeding when they are 3 to 6 years old and their gestation lasts about 10 to 11 months. Females are believed to give birth every other year to a single calf that measures about 2.5 feet long and weighs only 16 pounds. Vaquitas usually give birth between February and April.

LIke all whales, dolphins and porpoise, the Vaquita is of course a marine mammal. Unfortunately, the vaquita is also the world’s most endangered marine mammal. Currently, they are listed as “critically endangered” on the IUCN Red List.

Vaquitas have the smallest geographical range of any marine mammal. Nearly the entire population lives within a area less than 1/4 the size of metropolitan Los Angeles.

The Vaquita’s small and exclusive range overlaps with an endangered fish species that is slightly larger than the Vaquita itself. The fish known as the Totoaba – a large sea bass species. At 6 feet long and weighing 200 pounds, the Totoaba possesses a rather large swim bladder which makes them highly sought after in the Chinese black market trade.

The fish’s bladder is used in Chinese traditional medicine with the belief that it helps with human fertility – a claim that remains an unproven concept. Though the Totoaba is an endangered and protected species internationally, the fish are still illegally caught in large gillnets which also trap the small Vaquita as well.

Due to the ongoing illegal fishing in these Mexican waters, the Vaquita population is critically low. Today fewer than 25 Vaquita survive in the wild, the latest report from the the International Committee for the Recovery of the Vaquita indicate the total may even be fewer than 20 animals.

Though potential predators of Vaquita could include large sharks and killer whales, and they have some of the lowest levels of pollutants in their native habitat, researchers have determined that gillnets are the only true threat to Vaquitas.

To save the Vaquita, scientists and officials agree that the only solution is to totally eliminate fishing with gillnets within Vaquita habitat and by stopping the illegal fishing and wildlife trade of its neighboring endangered species, Totoaba. Without more drastic measures the world’s most endangered marine mammal species, the Vaquita, may soon become extinct in our lifetime.

Killer Whale

The world’s oceans cover 70 percent of the planet. Full of an abundance of life – from the tiniest plankton to the largest animal on Earth. Among the world’s vast diversity of life is a delicate balance of predator and prey in all shapes and sizes. In this undersea kingdom – one animal rules them all.

Swift and clever, visually stunning and physically powerful – it can kill anything that swims. It’s scientific name is Orcinus orca – but all over the world the top predator of the sea is known as the Killer Whale.

One of the most recognizable marine mammals, with their distinctive black and white bodies and signature dorsal fins, these apex predators are found in every ocean in the world, they are the most widely distributed of all cetaceans.

Despite their common name, Killer whales are the largest member of the dolphin family, Delphinidae. This group includes other large marine mammals such as Pilot Whales and Pseudorcas – sometimes known as False Killer Whales.

The common name Killer Whale came from ancient sailors who would witness them attacking other often larger whales. Historically they were first referred to as Whale Killers but the name was swapped over time and today they are an icon of the sea.

Different populations of killer whales around the world differ in size but males average between 20 and 30 feet in length, females are typically up to 18 feet long.

Easily recognized by their large size and striking appearance, the Killer Whales’ countershading coloration of dark black on top and bright white on the underside helps them blend in to their surroundings. When viewed from above, they seem to disappear into the dark depths below, yet when seen from below their bright bellies help mask them against the strong backlighting of the sun.

In addition to their coloring, the Killer Whales’ markings acts as a type of camouflage known as disruptive coloration – the large eyespots, the curving white on their sides and the marking known as the saddlepatch – a grey stripe or swirl behind their dorsal fin all help break up the killer whales body shape and even blend into the shadows and filtered sunlight of the ocean.

Another prominent characteristic is the tall dorsal fin on their back. Killer Whales have the largest dorsal fin of any marine mammal. Male’s dorsal fins may reach up to 6 feet tall.

Killer whales are found in a wide range of habitats, both open seas and coastal waters. While they are most abundant in colder waters like Antarctica, Norway, and Alaska, they are also found in tropical and subtropical waters.

Ongoing scientific studies have revealed many different populations that differ genetically, as well as in appearance, behavior, social structure, dietary preferences and feeding strategies as well as distinct vocalizations. These ecotypes of Killer Whales may even represent different species or subspecies of the Orcinus orca.

In the temperate coastal North Pacific, there are three different ‘ecotypes’ of killer whales. Identified as Resident, Transient (or Bigg’s) and Offshore Killer Whales.

The Resident Killer Whales are comprised of 3 distinct populations known as the Alaska, Northern and Southern Resident Killers Whales. These groups are fish eaters, notably chinook salmon.

The Southern Resident Killer Whale – is listed as endangered even though most killer whales worldwide are abundant. Found in the northeastern Pacific Ocean, along the coasts of British Columbia and sometimes Alaska and most famously in the Puget Sound of Washington. The current population of this group is the lowest it has been in 34 years.

A group of “Offshore” killer whales are found from California to Alaska, mostly along the continental slope, and sometimes even farther out to sea. Due to their habitat range, little is known about the Offshore killer whales but they are known feed on schooling fishes and sharks.

The ecotype known as Transient or Bigg’s Killer Whales are specialized hunters who frequently feed on other marine mammals such as sea lions and whales and are sometimes considered the “wolves of the sea.” These skilled hunters are found all along the North American coast. The Bigg’s Killers Whales are named after Dr. Michael A. Bigg – a Canadian marine biologist who is recognized as the founder of modern research on Killer Whales.

Other ecotypes around the world include the Antarctic Type A, B, C & D. Some of the Type B population known as Gerlache Killer Whales feed on penguins while Type A Killer Whales typically stay away from the ice and feed on Minke Whales. The Type A Antarctic Killer Whales are the largest known ecotypes, males may reach over 30 feet in length. The Type C Antarctic Killer Whales are the smallest with males only averaging 18 feet in length the size of most females in other ecotypes.

In the North Atlantic two groups are identified as Type 1 Eastern North Atlantic which prefer herring and mackerel while the Type 2 Eastern North Atlantic are similar to the Bigg’s Killer Whales and prefer marine mammals, mostly other whales and dolphins.

In waters off New Zealand, some killer whales are known to hunt and eat stingrays and sharks.

Killer Whales possess many incredible traits and abilities that make them such proficient hunters from camouflaged coloring, to strength and speed, the clever use of echolocation and their social skills of cooperation. A pod of Killer Whales on the hunt is considered by many to be one of the most impressive sights in the natural world.

Killer whales are among the fastest swimming marine mammals. They can swim as fast up to 30 mph but they usually travel at speeds of 2 to 6 mph. The main source of their propulsion is their large tail flukes. Comprised of tough, dense, fibrous connective tissue there are no bones or cartilage in a Killer Whale’s tail. The large muscular area between the dorsal fin and the tail flukes – known as the peduncle – is used to move the flukes up and down and give the Killer Whale their incredible bursts of speed – capable of propelling them high out of the water.

A primary trait of the killer whale is their vocalization ability. Killer whales produce sounds for communicating and they use echolocation for navigation.They produce a variety of sounds including whistles, echolocation clicks, pulsed calls, low-frequency pops, and jaw claps. A killer whale makes sounds by moving air between nasal sacs in the blowhole region.

Pulsed calls are the most common vocalization of killer whales. Experts believe these calls function in group recognition and coordination of behavior.

Echolocation is an ability used by toothed whales, some other marine mammals and bats. This advanced ability allos the Killer Whale to locate and even identify objects by emitting high-frequency sounds and clicks and listening for echoes. These sounds are at frequencies far beyond human hearing and each click lasts for less than one millisecond.

The sounds travel through the melon – the rounded region of a killer whale’s forehead – which consists of fatty tissue. The major areas of sound reception are the fat-filled cavities of the lower jaw bones. The sounds are then conducted through the lower jaw into the ear and auditory nerves.

The use of echolocation and calls may vary greatly between fish-eating and mammal-eating populations of Killer Whales. Those who primarily eat fish have been found to be more vocal while those who feed on other marine mammals have learned to use less sounds, since many of their prey species, which have more acute hearing could detect the Killer Whales presence. Another sign of the Killer Whales intelligent ability to problem solve.

Killer Whales are not only fast and powerful but they are also highly intelligent and social animals. A dominant female whale usually leads most social groups while males generally remain on the outside of the group, coming together to breed.

Killer Whales are famous for working together when hunting, whether corralling a school of fish or isolating a larger whale calf from its mother, they effectively communicate through vocalizations and body posturing to successfully capture their prey. Some Killer Whales have been observed swimming onto a beach to grab unsuspecting seals and many specialized hunting techniques are passed on to younger members of a pod.

A female Killer Whale may give birth every 3 to 10 years, gestation averages 17 months. While different populations of whales differ, most calves are typically around 8 – 9 feet long and estimated to weight between 250 and 350 pounds. The calf may nurse for a year or longer.

Killer whales have long fascinated people both in their ability to hunt and their curious nature and intelligent ability to problem solve. Most of what has been learned about killer whales has come from studying the Resident Killer Whales of the North Pacific Ocean though studies indicate that there is still much to learn about the many varied populations around the world.

Throughout the world’s oceans, a vast and diverse kingdom of animal life thrives in a delicate balance of predator and prey – but one animal reigns supreme – the Killer Whale.

Acknowledgements

Special thanks to the following organizations for their education, research and conservation programs that provided information for this episode:

Aquarium Of The Pacific
NOAA Fisheries – Vaquita
NOAA Fisheries – Sea Turtles
Sea World’s Animal Guide

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