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a Marine Scientist: answers to Bird and Reptile questions! Index to Questions SEA TURTLES SEA SNAKES
SEA BIRDS
SEA TURTLES
Q: What do sea turtles eat? How long do they live? How long can they stay under water? A: Sea turtles have different diets, depending on the species. Green sea turtles are herbivorous, and feed mainly on algae and sea grasses. Hawksbill turtles feed mostly on sponges while Kemp's ridley sea turtle eat crabs and other crustaceans. Leatherbacks, the largest sea turtle, feed primarily on jellyfish. This can cause problems because floating plastic bags are easily mistaken for jellyfish by the turtles, and can cause mortality. Loggerheads eat crabs, jellyfish, and molluscs. Other sea turtle have similar diets. Sea turtles can dive for as
long as 2 hours. Not much is known about the ages that sea turtles can attain. It is assumed that once sea turtles reach sexual maturity, they are reproductively active for around 30 years. Seeing as some species don't reach sexual maturity for 50 years, an 80 year lifespan seems reasonable. Turtle age is determined by the growth rings of the scales on a turtle's back. Scientists count these rings and use a mathematical formula to determine age. Unfortunately, most sea turtles never reach maturity because of human impacts on their lives. The impacts include the destruction of turtle nesting ground for development, poaching of eggs and adults for food, death by ingesting garbage or becoming entangled in fishing nets and line, or six-pack holders. Thousands drown in shrimp nets, and some die from collisions with boats. Human disturbances such as trash or bright lights on a nesting beach can cause a female to return to the ocean without laying her eggs. Babies, once they hatch, may become disoriented by city and street lights. These reasons are why all the sea turtles found in US waters are on the endangered species list.
A. Scientists recognise 8 different species of sea turtles in the world. They generally live in tropical seas, and come up on sandy beaches to lay their eggs. The different species are: Green Sea Turtle Chelonia
mydas For much more information
about sea turtles, check out the excellent Sea Turtle Research
Program web site at Texas A&M University In
addition to accurate information and pictures, there is also
an excellent page of links to many other sea turtle sites.
Q: While on vacation in Panama City Florida, we saw a nest where a sea turtle had laid her eggs, and our question was: about how long will it take for the eggs to hatch? Thanks A. There are several different species of sea turtles, and the incubation times for each are slightly different. Most females nest every 2-4 years, 1-8 times a season. At night, the females crawl onto the beach and dig an urn-shaped nest hole. Approximately 100 spherical eggs, the size of golf balls, are deposited in the nest, where they incubate for approximately two months. After hatching, the juvenile tortoises make their way to the ocean using light cues. Sexual maturity takes about 20-30 years for most of the sea turtles species.
Q: tell me why sea turtles lay their eggs in the sand instead of in the ocean A: Wow, what a great question! I researched your question and did not find a definite answer. However, I can give you some possible reasons for why sea turtles lay their eggs on land instead of in the ocean. To begin, I must tell you about how turtles evolved. Turtles have lived on earth for a long time. The first turtle fossils found date back to Triassic period, the age of the dinosaurs, some 200 million years ago. The immediate ancestor of turtles is still a mystery, but we do know that all reptiles (including turtles) evolved from amphibians, who in turn evolved from fish. Therefore turtles were first land animals, and some species, like sea turtles, went back to living aquatic environments. All turtles lay eggs, none produce live young. Turtle eggs are similar to bird eggs, in that the eggs have a hard shell. The eggs can stand some saltwater (when the tide covers the nests), but if there is too much freshwater the babies within the eggs will die. Since turtles evolved on land and then some moved to the ocean, their eggs are originally terrestrial. It would be difficult to evolve a new egg that can withstand harsh aquatic environments.
A. Leatherback turtles, Dermochelys
coriacea, are found in all oceans, from Labrador, Iceland,
and Fishing nets can be a hazard for marine turtles too. Some fishers now use Turtle Exclusion Devices on their nets, so that the sea turtles do not get caught. The shell of the leatherback
turtle is (as you might expect!) very leathery, and is not used
for making objects in the same way as other turtle shells (especially
Hawksbill turtle shells).
Q: What's the difference between a tortoise and a turtle? A: Tortoises,
turtles and terrapins all belong to the Order Chelonia. Those
species which live exclusively on land are usually referred to
as tortoises, while aquatic species are called turtles. Freshwater
turtles are sometimes called terrapins. For some information
on sea turtles, check out the Turtle
Trax web site.
Q: I've heard that during the incubation period of turtle eggs, temperature often determines the sex of the turtle. Is this true and if so why? A. Yes, it is indeed true
that for several species of sea turtles, the incubation temperature
determines the sex of the resultant offspring. According to J.D.
Miller, this is true for the turtles Chelonia mydas, Lepidochelys
olivacea, Caretta caretta , Chelonia depressa,
and At cooler temperatures, (26-28 degrees C), males will tend to hatch. When the temperatures in the nest are warmer (32 degrees C), the hatchlings will be female. Researchers are able to calculate the temperature at which half the offspring will be male and half will be female - this is known as the SDT50, or the Sex Determining Temperature at which 50 % of the turtles will be male, and 50% female. As far as why this is the case, it is open to speculation. Often, a female will lay several nests over a season, so some of her nests will consist of males, some females and some nests will have both sexes. It is possible that it is better for the survival of the animals if females hatch and make their way to the sea during warmer weather. If anyone out there has a better theory, we'd love to hear it!
Q: I need to know, for a report on sea turtles, how they benefit humans, and if they are a hindrance to humans in any ways.
A: Ask not what the sea turtle
can do for you, but what you can do for the sea turtle. Sea turtles
add to the biodiversity of life, and in that way they benefit
humans. They are beautiful and long lived organisms, but unfortunately
they are under some stress, and are considered endangered. If
anything, humans are a hindrance to sea turtles. Here are three
web sites that I strongly recommend, as they have good information
on the status of sea turtles:
Q: Why do sea turtles usually migrate to Brazil or Florida? A: There is currently much ongoing research about the migration patterns of different species of sea turtles. Research groups from around the world have put tracking devices on turtles in order to monitor their movements. The really amazing thing about sea turtles is that they spend most of their lives in the ocean, but when females return to land to nest – they come back to the very same beach that they were born on! So the turtles that migrate back to Brazil, or Florida is turtles that were originally born there. It is believed that the turtles can use magnetic cues in order to orient themselves to the proper beach – even from the middle of the ocean. Scientists are still doing research on how long sea turtles spend in the ocean, or where they go. If you are interested in finding out more, try looking up the following website: http://www.cccturtle.org/sat1.htm
Q: How do T.E.Ds work? A: A T.E.D also called a Turtle
Exclusion Device (and sometimes referred to simply as a BRD or
Bycatch reduction device) is a modification to prawn trawl nets
which, while retaining prawns, allows turtles to escape. A TED
is a metal grid sewn into the net which guides turtles to an
opening in the net. Shrimp pass through the grid and into the
back of the net. These pages from the Sea Turtle
Restoration organization are also helpful.
Q: How do sea turtles hold their breath so long? A: Sea turtles are excellent divers. Leatherbacks routinely dive more than 305 m (1,000 ft.), and they may reach depths of more than 1,190m (3,900 ft.) seeking jellyfish. Since they are ectothermic, sea turtles have a slow metabolic rate. This slowed metabolism allows them to stay submerged for long periods of time. During long dives, blood is shunted away from tissues tolerant of low oxygen levels toward the heart, brain, and central nervous system. Leatherbacks have high concentrations of red blood cells; therefore, they can retain more oxygen. The muscle of leatherbacks has a high content of the oxygen-binding protein myoglobin. Myoglobin transports and stores oxygen in muscle tissue.
Q: I need information about Fort Lauderdale, FL. My class is doing a problem about loggerhead tutles, the Atlantic ocean and the food chain involved in that system, etc. Can you help me? A: All species of sea turtles
are greatly influenced by human impact. All five species of sea
turtle in the US are on the endangered species list. Turtles
are hunted for meat, leather, and in some cases, their shells.
The turtles have also been placed at risk due to habitat destruction
of their beach nesting areas. Loggerhead sea turtles feed on
jellyfish. They can often mistake plastic garbage for their favourite
snack, and die when the plastic blocks their digestive system.
There are many conservation groups who strive to protect the
sea turtle. I suggest checking out some of these great sites
for more information:
Q: How do you tell male and female turtles apart? A: Being able to tell a boy
turtle from a girl turtle is actually very hard for a lot of
people. The following information is a general description of
the differences between girl and boy turtles.
SEA SNAKES
Q: I am going to Palau in the spring and want to know anything you can tell me about sea snakes, especially in and around Palau. A. Sea snakes are found in the Family Hydrophiidae, and are close relatives to elapids (cobras and kraits). All have fixed fangs and potent venom. Sea snakes are air breathers and must surface to breathe. Their tails and body are flattened laterally, making them efficient swimmers. They can dive from 20 to 90 feet but have been found as deep as 500 feet! Most sea snakes feed on eels and other fish so they do not venture into water that is too deep for their prey. Sea snakes mate in water and give birth to live young. Most sea snakes are inoffensive and are only dangerous if they are provoked. In fact some sea snakes, like Laticauda are extremely docile and children in Fiji pick them up and are rarely bitten. There are species that are more easily provoked and may bite if they are stepped on or handled roughly. Only a small percentage of people bitten my sea snakes actually show signs of poisoning. In fact there is only a 3% fatality rate of people who were injected with poison and received medical treatment. The distribution of sea snakes is concentrated in tropical waters, as they are cold blooded and regulate their internal body temperature from the external environment. Most species of sea snakes are found in the Indo-Australian region and one species (Pelamis) lives along the coast of North America. No sea snakes live in the Atlantic Ocean. There is a high density of of sea snake populations in Philippine waters, but only 12 species live there. Specifically in Palau I am uncertain of how many sea snakes species are found there. Don't worry too much about sea snakes, I'm sure by just being aware of them you will be fine.
SEA BIRDS
Q: How many kinds of penguins
are there? Do penguins breathe under water? What do penguins
eat? How many eggs does a penguin lay at one time? Penguins, like all other birds, do not have the ability to get their oxygen from water (as fish do) so they must breathe air. Although penguins dive for their food, most species do not spend longer than 3 minutes under the water. The emperor penguin holds the record for the longest and deepest dive at 265 m (870 ft) for a little over 18 minutes. Even still it is rare for emperor penguins to spend more than 6 minutes under the water without coming up for a breath of air. Although many penguins spend a lot of time on land, all penguins feed only on marine animals. A penguin's diet is usually made up of crabs, shrimp, fish and squid. Most penguins will eat whatever is available but some penguins, like the adelie penguins are picky eaters and will only eat one or two kinds of food. Penguins typically lay two eggs per breeding season with an interval of one to five days between them. Sometimes if one or both of the eggs are lost two more will be laid.
Q: How long does a penguin usually live? A: So far we don't know exactly
how long penguins live. One scientist believed that a healthy
penguin will live to about 34 but this was based on penguins
in captivity and might not be right for birds in the wild. At
least it gives you an idea. Q: Can penguins hurt humans? A: As far as is known penguins
have done little harm to humans, aside from a nip or two when
they have been annoyed. As with any wild animal though penguins,
if provoked, could potentially do harm and should be watched
at a distance and respected in their territory. Q: How tall are penguins? A: On average penguins only
stand about two feet tall, however heights ranges a lot depending
on which species or kind of penguin you're talking about. The
largest of the penguins, the emperor penguin, grows to about
39 inches and the smallest penguin, little blue stands no more
than 14 inches tall. Q: Why dont penguins feet stick to the ice? A: Interesting question.
Penguins are unique in that they are more completely covered
in feathers than almost any other bird. This indeed includes
their feet. When a penguin's feathers are lying flat, the scale-like
exposed parts overlap and form a surface that is practically
impermeable to wind and water. Furthermore, the shafts below
them are tufts that form an insulating layer. On top of all
this, penguins secrete oil into their feathers, as do other
birds, to prevent water penetration. I believe, and I'm only
speculating here, that the insulating properties of the penguins
feet, tight-knit feathers and secreted oil, would prevent their
feet from sticking to the ice when they hop out of the water.
Q: Why do puffins live in burrows? A: Puffins are ready to mate when they are five years old. They return from the water to the same location where they were born to find a mate; they keep these mates their entire lives. The puffin pair will then form a nest either in a rocky crevice, or by digging a burrow. The pair finds each other every breeding season by returning to the same burrow. Pufflings (baby puffins) stay in the burrow for six weeks, and their parents bring them fish to eat. If the baby puffins, or eggs, were not in burrows, then it is likely that they would be eaten by predators, such a seagulls!
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