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ASK A SCIENTIST: ANSWERS TO QUESTIONS Seals | Sea Lions | Sea Otters Index to Questions SEALS & SEA LIONS SEA OTTERS MANATEES & DUGONG
WALRUS SEALS & SEA LIONS Q: How much do seals eat a day, and how long do they live? A: There are so many different seal species in the world that its difficult to say what they can eat in a day. The harbour seals at the Vancouver aquarium eat an average of 8.1 percent of their body weight each day. That's a lot of food! If a 100 pound human had to eat eight percent of his weight each day it would mean consuming about eight pounds of food. The average lifespan of all pinnipeds (seals, sea lions and walruses) is about 15-25 years.
Q. I am drafting a research
proposal for my Biology 208 class, and would like to know if
there is any information on harbour seals effect on the local
fisheries populations on the Pacific coast, and if the harbour
seals are a major problem.
Q: Humans can hear frequencies of 20 - 20000 Hz. What is the range of frequencies that seals (Phocidae) can hear under water? A. The range of frequencies that seals can hear tends to vary slightly depending on the species. The hair seals (Phocidae) can hear frequencies ranging from 1000 to around 100,000 Hz, with corresponding thresholds of 70-130 dB (re 1 uPa). The eared seals can hear frequencies between 300 and 60,000 Hz with a 60-140 dB threshold range. For more information on communication in mammals, I would strongly recommend the following book (it is probably one of the best): Richardson, W.J, C.R. Greene, Jr., C.I. Malme and D.H. Thomson. 1995. Marine Mammals and Noise. Academic Press, New York. ISBN 0-12-588441-9. Thank-you to Dr. Ben Wilson for help with this query
Q: Do the harbour seals
like those in the Baltimore National Aquarium, exist within
the Potomac River?
Q:Why can a Californian Sea Lion hear the baby in a hoard of babies with good hearing? A. I think you are wondering how a female can identify her sea lion pup when there is a big group of them that all look the same. The reason why she can identify her pup is because each female has a slightly different vocal pattern. The pup can identify its mother by the distinct band of frequencies that are present in her vocalizations. When we sing, we have different pitches that we can sing (do-ray-me-fa-so-la-ti-da). If you think of a sea lion's call being made up of lots of different pitches, like a chord played on a guitar or a piano, then you will have a better understanding. Each female has a unique chord that she sings, which the pup can identify. So even though there might be a hundred pups in a sea lion colony, the female can always identify her own pup using her own unique vocalizations.
Q: Why do Sea Lions bark like dogs? A: It is only the California sea lion that bark, Stellar sea lions roar. California sea lions bark, because it is the type of vocalization that their vocal cords permit. Just like how dogs bark and humans talk, it is physiologically the sound that our vocal cords produce. Now why California sea lions bark is to communicate with other sea lions. Male California sea lions have a loud, directional bark that is used to threaten other males and to show their dominance over other males during breeding and non-breeding seasons. Some scientists have suggested that male California sea lions bark to attract other males and sub-dominant males will often vocalize more than the dominant males. Sea lion pups and mothers will also bark to find each other when they are separated. California sea lions will also produce underwater vocalizations that include, loud barks, whinnies, faint clicks, moans or humming sounds, chirps, belches, and growls. Underwater vocalizations seem to be used by sea lions during breeding seasons, especially males, to assert dominance and define territories.
Q: Are there any known breeding areas for Stellar or California Sea Lions along the Vancouver Island Coast? Where are the usual breeding grounds for these two marine mammals? A: Both California and Stellar sea lions breed on islands off the mainland. There are no breeding grounds for California sea lions near Vancouver Island. In fact, their closest breeding grounds are in Oregon. There are breeding grounds for Stellar sea lion off Vancouver Island. Vancouver Island is the location of the most southern Stellar breeding and pupping grounds. Off the northern tip of Vancouver Island is a chain of islands called the Scott Islands and Triangle Island that are known Stellar breeding islands. Another island thought to be a Stellar breeding island, but not yet documented, is Sointula Island, located near Port Hardy. Scientists have observed Stellar sea lion pups on Sointula Island. Other Stellar breeding islands are located north to Alaska.
Q: What kind of cells do seals have? A: Seals are mammals just like you and me and threfore they have basically all the same kinds of cells that we do: blood cells, muscle cells, skin cells, brain cells etc. However, they do have special adaptations in their cells and systems which allow them to live in the marine environment. Many of their physiological adaptations have to do with their dive response. For example, because they need to hold their breathe for long periods of time, seals need a way to hold lots of oxygen. Their red blood cells have a higher concentration of hemoglobin (a oxygen bonding protein) and their muscles cells have a higher concentration of myoglobin (another oxygen bonding protein).
Q: How do the seasons influence the Harbour Seal's behaviour? A: The most important seasonal
event that effects harbour seal behaviour is the breeding season.
Seals have annual reproductive cycles and here on the Pacific
Coast, females give birth in June-September and are ready to
breed soon after. During this season, males are more aggressive
and often fight over females. Moulting season (when the seal's
shed their skin) also happens once a year usually right after
breeding season. Harbour seals are non-migratory but they will
follow food sources. In the fall, you can see seals congregating
at salmon stream estuaries hoping to feed on spawning fish.
Q: How are whales different than seals? A: Whales and seals are both marine
mammals, so they are the same in many ways. They both need to
breathe air from above the water’s surface, and they both
give birth to live young instead of laying eggs. Also, compared
to most ocean creatures, seal and whales are both quite BIG.
SEA OTTERS
A. We spoke to Dr. Jane Watson at Malasina University College. She and her colleagues have a paper that is currently in press, and should be out shortly:"Updated status of the sea otter Enhydra lutris in Canada. in press. Watson J, GM Ellis, TG Smith, JKB Ford. Canadian Field Naturalist" This would give you the most
up to date information on the distribution of the sea otter in
British Columbia.Note that there are no archaeological records
of sea otters in the Straight of Georgia, but there have been
otter bones found in middens off the Straight of Juan de Fuca.(Answered
with the assistance of Dr. Jane Watson)
Question: How many urchins does a sea otter normally eat a day? A. Although sea otters do enjoy eating sea urchins, this is not their only food! They also eat mussels, abalone, clams, scallops, crabs, snails, chitons, octopus and squid! They certainly do eat a lot, however - in order to maintain their body heat, they have a very high metabolic rate. This means that they must eat a lot - estimated to be about 25% of their body weight per day. We can therefore make an estimate of how many sea urchins a sea otter would eat in a day (assuming that it did not eat any other of its favourite foods!) A full grown male sea otter
weighs about 40 kilograms. This would mean that he would eat
25% of that per day, or 10 kilograms of food. If we estimate
the weight of a red sea urchin as 200 grams, then our hungry
sea otter would have to eat about 50 urchins per day. Remember,
this is certainly a rough estimate!
Q: How do sea otters eat? A: Sea otters feed on many
types of marine invertebrates (animals without backbones) that
live in and For more information on sea otters check out our sea otter web page and our Sea Otter Stewardship site!
Q: What do sea otters drink? Do they drink the sea water? A: Water can
be a bit of a problem for marine mammals. Some mammals get all
the water that they need from the food that they eat. Others
drink salt some water. Either way, they need to put a lot of
energy into getting rid of all the salt that is in their body.
Q: Do Sea Otters have blubber to keep them warm if they live off the Alaska coastline? A: Sea otters keep warm in Alaska, not by having blubber but by having extremely dense fur. In fact, sea otters have the thickest fur of any mammal on earth! In one square centimetre there are more hairs on a sea otter's fur than there is on your entire head! Sea otters have two layers of fur, one is a dense down layer close to their skin and the second layer consists of longer, coarser hairs that extend above the down layer. Sea otters keep extra warm by constantly grooming themselves, they blow air into their fur, that gets trapped in the down layer and therefore provides a warm insulating air layer next to their skin. For more information on sea otters check out our sea otter web page and our Sea Otter Stewardship site!
Q: What information do you have on the recent decline of the Alaskan sea otter? A: For Northern populations of sea otters, salmon gill nets are still a major cause of mortality. Presently in Alaska, the illegal shooting by fishermen and the legal hunting of otters by Indigenous Peoples are believed to be the main causes of mortality. Brown bear predation and eagle predation of pups have been observed, but their contributions to mortality are considered to be minimal. Another possibility is that recently transient Killer Whales have been eating the sea otters up in Alaska. The normal food source of transient killer whales are sea lions. Recent drastic declines in the Stellar sea lion populations in Alaska resulted from a decline in pollock stocks (a fish that is the main food source for sea lions) due to overfishing. When the Stellar sea lion populations crashed the transient killer whales lost their major food source and had to find a new food source, sea otters. Sea otters are not normally eaten by transients because they have hardly any nutritional value, but with no other food readily available the choices are limited. I do not have a reference for the recent transient predation on sea otters, if you have one I would love to hear from you.
Q: What is the life expectancy of a sea otter? A: The life span of a sea otter has only recently been known by scientists. The average life expectancy of a sea otter is 15 years.
Question: effects of oil on sea otters A. Oil is very detrimental
to sea otters. See the OceanLink web page on sea otters for more
information.
A. To answer your question, we contacted Dr. Jane Watson, who has studied the sea otters on Vancouver Island for a number of years. The Kyoquot Band has published a brochure, in conjunction with BC Parks and the Haida Watchman programme, on the area where sea otters are found. The brochure makes recommendations about how to camp, and how to be a responsible otter watcher. Dr. Watson generally recommends that people not approach otters closer than 100m and that they leave mothers and pups entirely alone. People rarely realize how many time a day a group of animals can be disturbed by well-meaning folks. Otters in and around the village of Kyuquot are most used to people and boats, so are generally the best otters to watch. Of course the absolute best otters to watch, and get up close to are the ones at the Vancouver Aquarium. Otters do well in captivity, seem to habituate, and behave fairly normally, says Dr. Watson. Incidentally, we're not sure if you plan on simply popping over to Vancouver Island, renting a boat somewhere, and spotting otters all over the place. You generally can't find sea otters on the east side of Vancouver Island. There is a small ecotourism industry developing in Kyuquot. There is one company operating out there, and have been doing so for over 20 years now: West Coast Expeditions
Q: I'm trying to answer questions about how otters react with humans? Are they afraid? Are they friendly? Do they enjoy being with humans? Do they bite? What would they do if you came near one? Thank you. I have looked at so many web sites tonight and could not find answers to these questions in the answer file. A: Sea otters are wild animals and react like any wild animal, unpredictably. If you provoke sea otters they will bite and they have very sharp teeth that would leave a nasty injury. There have been some occasions where wild sea otters have been quite friendly with photographers and researchers. Sea otters in Aquariums are not necessarily friendlier either. In fact at the Vancouver Aquarium, the staff have to put on protective gear if they want to move a sea otter to a different location. It all depends on the situation and personality of the sea otter as to how they would react to humans. They are kind of like dogs in how they react, some will bite and hiss and some will be friendly.
Q: What are the mating habits of Sea Otters? A: Sea otters do not remain in male-female mated pairs for very long. Normally, sea otters float on their backs, but a male seeking a reproductive (estrous) female will swim on his stomach and will often climb out on rocks looking around for a suitable mate. When the male has located a female they will undergo a pre-mating ritual which lasts about an hour. They play with each other in the water, and often become quite aggressive. When the female is ready to mate she lays on her back in the water and arches her back. The male mates her from behind, and often both animals are below the surface. After mating, the pair "hauls out" at a site chosen by the female and then groom each other and go to sleep. The pair stays together for about 3 days, after which the female sneaks off, often when the male is diving for food.
Q: How is the sea otter adapted to its environment? A: The sea-otter has a few different traits that allow it to live quite happily in the ocean environment. Firstly the sea-otter has eyes that allow it to see quite well in both the underwater and land environments. This helps out because the sea-otter lives in both environments. Secondly the sea-otter has a lot of insulating fur to help keep it warm. This fur is necessary because unlike other mammals such as seals, walruses and so forth the sea-otter does not have insulating blubber. Thirdly the sea-otter is able to drink salt-water without any ill effects. The sea-otter appear to drink this sea-water to assist in eliminating urea from its body. If us humans tried to drink sea-water it would have incredibly bad health effects and eventually would kill us! So it appears that the sea-otters are well adapted to their environments.
MANATEES
Question1:What Do Manatees
Eat? A. 1. Manatees are vegetarians. They eat sea grass and other vegetation such as algae that they find in the shallow waters that they live in. 2. We've never heard of this, but it does seem possible for an alligator to attack a manatee. 3. There are many different species of dolphins. The depth that they dive to generally depends on what sort of fish they usually eat. A river dolphin such as the Ganges Susu would not have to dive as deeply to get fish as an Atlantic White sided dolphin. Dolphins usually don't dive very deep, and certainly don't hold the record for cetaceans. The sperm whale has been known to dive as deep as 3000 meters! 4/ Again, there are many species of dolphins, and they eat a wide variety of types of fish.
From the Mote Marine Lab in Florida: Answered by Dave Hutchinson
Q: What is a dugong. Where can I find information on it. A: I believe you mean "dugong". They are large marine mammal herbivores that live in Asia. They are closely related to the manatee and to the extinct Stellar's sea cow. They are endangered through boating collisions and habitat destruction. To find lots of web pages devoted to them, check out the Australian Government's Conservation of Dugongs page.
Q: Can you tell me about Manatees? A: Manatees live in rivers
or salty estuaries, and rarely venture into the open sea. The
West Indian manatee has a range from the Gulf of Mexico to Brazil.
The Brazilian manatee is found only in the Amazon river in Brazil,
and nowhere else. The African manatee is found along the coast
of West Africa, and further inland in the river systems. They
move around seasonally to find warmer waters in the winter. Interesting
fact- if manatees get to cold, they become constipated and die,
that's why they must find warmer water. What do manatees eat?
Well, every day they eat around 10% of their body weight in grass
and seaweed. That means that each day they eat between 100 and
200 lbs of food! Manatees are vegetarians, but the protein in
their diet comes from tiny animals that live in the plants they
feed on. Manatees are normally solitary animals, however females
take care of their young for 1-2 years. Mating season is a different
story. Up to 17 males
A: A: For the most part Manatees live in rivers and saltwater estuaries. Manatees rarely venture into the open ocean. Manatees move around to find warmer water when the water becomes to cold for them to live. Manatess are currently endangered from habitat loss. Tell Dakota thank you for her question as its very advanced for a five year old.
Q: Why are Manatees being spotted further north on the Atlantic specifically around North Carolina? A: Manatees do migrate north as long as the water stays above 68 degrees Farenheit. In 1995 a Manatee named Chessie migrated all the way to Rhode Island and then back to Florida when the water became to cold. From the research I did Georgia and South Carolina's waters are warm enough in the summer for Manatees to live happily. When the water in these areas becomes to cold the Manatees migrate back to Florida again.
WALRUS Q: I would like to know what type of animal the walruse descended from? A: Most scientists believe that the walruses evolved from a group of animals called Phocids about 20 million years ago. Phocids include all of the seals that do not have external ears on their bodies.
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around
kelp forests. Some of their favourite foods include crabs, abalone,
sea urchins, clams, and sea snails. Sea otters first must find
their food before they eat it, so they will dive in waters usually
between 10 to 20 metres deep. They find their food mainly by
touch, because their underwater vision is limited. Sea otters
can only hold their breath for a short period of time and therefore
spend only about 74 to 246 seconds underwater when they dive.
When a sea otter finds a food item they like, they will swim
to the surface of the water and this where they eat their food.
Sea otters have extremely dexterous (flexible) front paws that
help them hold and manipulate their food. They always lay on
their backs with their stomachs up and heads out of the water
and they use their chest as a dinner plate. How a sea otter eats
depends on what they are eating. If they are eating crabs they
will pull off the pinchers (so they don't get pinched) and proceed
to finish off the rest of the crab without being pinched by the
crab's claws. If they are eating a hard shelled animal (clams,
urchins, abalone, etc.) they usually have a flat rock that they
use to smash the hard shell open on their chest, therefore their
fork and knife is their front paws and the rock and their dinner
plate is their chest. In fact, some sea otters take their favourite
rock and stick it in their armpits for safe keeping, until they
need to use it again, pretty cool!!!
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