After watching a seal battling along on land one doesnt eactly get filled with awe but wait until its in its watery element and they are fast, agile and responsive.
Seals prefer cold water and have a thick layer of fat called blubber which helps insulate themselves from the low temperature water. They are particularly fond of arctic and antarctic waters.
They typical adult weighs between 100 lb (45 kg), being 3.3 ft(1 m) in length (Galapalos Fur Seal) and 8 500 lb (3850 kg) being 23 ft (7 m) in length (Southern Elephant Seal).
Most seals feed off primarily fish although crustaceans and even birds may be taken occasionally.
Although seals ore so adept at swimming they can often be found outside their element on rocks or other forms of land. This is normally to escape predators such as sharks and orcas. Additional reasons for being outside the water are for breeding, molting and feeding young pups.
How deep can a seal dive? Like all things, it depends who you are.
A southern Elephant seal can dive to almost 5000 ft (1500 m) and has been found to have more carbon monoxide than most people. This is significant as it has to do with limiting oxygen being moved in the blood. A dive of this nature they typically perform for 2 hours. Looking at all the adaptations scientists can only explain about 59 minutes of the two hours according to the Smithsonian Magazine.
Adaptations include the ability to use their spleens as scuba tanks providing more oxygen when needed as well as the muscles being ‘oxygenized’ before the dive. Couple this with a slowed heart rate and ability to constrict blood vessels limiting blood flow to the peripherals, its still a pretty tall order to fulfill and that’s without even considering the pressure that the animal is under at those depths…
Leopard seals are the dark side of the family with specific adaptations for eating prey such as penguins and also other seals. The leopard Seal swims under ice flows and waits for prey which may arrive in the form of other seals and penguins. This ice flow is normally where a penguin colony resides. When a leopard seal catches a penguin it will thrash it around in the water like a dog catching prey before eating it.
The predatory nature of the leopard seal can be further seen in the strong jaw muscles and the long curved canine teeth.
New Zealand fur seals are particularly interesting in terms of their reproduction as the female gives birth and then mates again within a few days! This would be before going out on her first foraging trip. This ensures that the next years pup is born in the warm summer months.
These seals are unique in that although the egg is fertilized it does not implant itself in the wall of the uterus for another 3 months ensuring that the next pup is not born while she is still caring for last years pup!