Conservation ». Tips ». Don't Feed Wild Dolphins. The Fisheries. Want To Do More? The Challenge. The Pollution Problem. Personal Choices. Direct Threats. Indirect Threats. You Can Help. References and Sightings. Endangered Species ». River Dolphins. Northern Right Whale. Bowhead Whales. How to Help. Marine Mammal Laws ». Enforcement Agencies. Relevant Legislation.
Government Permits and Licenses. Alliance Accreditation. Manatee Rescue Permits. Marine Mammal Info ». Dolphin Info ». Natural History. Sea Lion Info. Manatee Info ». Fact Sheet. Training ». At DRC. Strandings ». Case Studies. Coloring Pages.
Just For Kids. Marine Animals Station ». Sea Lions. Games Zone ». Wacky Words. Sea Riddles. Word Searches. Ocean Clean-up Game. Conservation Corner. Dolphin Camp. Career Opportunities. Working at DRC ». Profile of Dolphin Research Center. DRC Environment. DRC Staff Profile. Educational Requirements. Salary and Benefits. Working in the Field ». Training Institute.
Occupational Assoc. Degree Program. Animal Trainer Certificate Program. Book Now. Sea Lion Info There are 33 species of pinnipeds meaning "wing-" or "fin-footed" which include 18 true seals, 14 eared seals sea lions and fur seals , and 1 walrus.
Seals vs. Sea Lions: Is there a difference? How fast can a sea lion swim? How long do sea lions live? What do sea lions eat? Do sea lions have good senses? How do sea lions sleep? How do sea lions regulate their body temperature? Do sea lions molt? How do sea lions scratch? How large are sea lions?
How long can a sea lion hold its breath? Where do California sea lions live? Do the sea lions at DRC take vitamins? Do California sea lions have predators? Breeding Once a sea lion becomes sexually mature, at around age four or five, they are able to breed. Create a list of articles to read later. You will be able to access your list from any article in Discover.
By looking at the flippers of seals and how they move through water, researchers have been able to show how distantly related seals have both evolved a similar form to deal with chasing down fast-moving prey. Despite living in the same environment and doing largely the same things, seals have evolved two distinct ways to swim. One group of seals chiefly use their feet to propel them through the water, while the other uses their flippers to swim.
This is curious, as both groups evolved from the same land-dwelling ancestor that slipped into the sea around 30 million years ago.
New research looking into how and why these two groups evolved such different swimming styles has combined anatomical and live animal observations with a team of engineers and computer simulations to figure out exactly what is going on. The researchers, based at Monash University but also including Museum scientists, found that both groups of seals were indeed using their flippers and tails to swim in different ways, but crucially that seals which used to swim with their tails can actually evolve to swim with their flippers, as is seen with Antarctic leopard seals.
Associate Professor Alistair Evans, from Monash University and who collaborated on the study, says, 'Wing-like flippers help leopard seals to surge forward and ambush fast-swimming penguins.
It seems likely that the earliest sea lions also needed this extra speed to capture their preferred prey: schooling fish. Seals that live predominantly in the northern hemisphere, such as grey and harbour seals, are from a group known as the true seals, or phocids. These have stubby, clawed paws which they can use to manipulate food and propel themselves through the water using their feet.
But it also includes one prominent outlier: the leopard seal. These huge predators live in Antarctica where they hunt down speedy penguins, and instead have incredibly streamlines front flippers. Sign In or Create an Account. Advanced Search. User Tools. Sign in. Skip Nav Destination Article Navigation. Close mobile search navigation Article navigation. Volume , Issue Previous Article Next Article. Article contents. Materials and methods.
Article Navigation. How fast does a seal swim? Variations in swimming behaviour under differing foraging conditions Susan L. Gallon , Susan L. This site. Google Scholar. Carol E. Sparling , Carol E. Michael A. Fedak , Michael A.
Martin Biuw , Martin Biuw. Dave Thompson Dave Thompson. Author and article information. Jean-Yves Georges. Martin Biuw. Dave Thompson. Accepted: 09 Jul Online Issn: J Exp Biol 18 : — Article history Accepted:. Cite Icon Cite. View large Download slide. Swimming speed in relation to patch distance and prey density was assessed using linear mixed effect models in R v2.
Therefore we calculated an index of transit swim speeds from visual data for each dive for each animal. Buoyancy at the surface and at 1 m and 2 m depths was calculated by adding the density of the diving lung volume DLV for these different depths to the density of the seal.
Table 1. Swim speed m s —1. All distances. Seal ID. View Large. Table 2. Table 3. Buoyancy values at different depths for seals where body composition was available. Buoyancy N. Mass kg. DLV 1. With no air in lungs. At the surface. L Mar There was no clear relationship between body mass and swimming speed in our study. Because drag scales to surface area while available power scales to body mass, larger animals should be capable of higher sustained swim speeds Feldkamp, ; Videler and Nolet, ; Stelle et al.
However,animals would be expected to swim at or close to their MCT speed during ascent and descent and the relationship between mass M b and MCT speed is not obvious. MCT speed scales to M 0. While this is apparent over the size range investigated by Videler and Nolet 0.
The broad-scale allometric relationship, which was determined across swimmers from many taxa, is due to the fact that drag coefficient C D decreases as Reynolds number Re increases over a wide range of Re values, and Re scales linearly to body length. List of abbreviations. Beauchamp, G. Beck, C. Biuw, M. Bowen, W. Charnov, E. Crocker, D. Davis, R. Dunstone, N. Fedak, M. The distance to the feeder and the rate of prey food delivery could be varied to simulate different feeding conditions.
Diving durations and distances travelled in dives recorded during these experiments were similar to those recorded in the wild. Mean swim speed decreased significantly with increasing distance to the patch, indicating that seals adjusted their speed in response to travel distance, consistent with optimality model predictions.
0コメント