by Deneice Arthurton

Created on: February 18, 2011   Last Updated: February 21, 2011

The scientific order Pinnepedia is subdivided into three families – Otariidae which comprises of sea lions and fur seals, Phocidae which are the true seals and Odobenidae, the walrus. There are far more shared features between the sea lion and the seal than there are differences but where differences do occur they are most easily distinguishable when these marine mammals are moving about on land.

Both seals and sea lions have four flippers and when the animal is at rest often little or no variance can be seen between then. However, the sea lion's rear flippers rotate forwards on either side of their bodies giving them four very separate appendages. This difference is of great significance in observing how the animals in question move when on land. The rotating flippers allow the sea-lion to move as if they are walking or waddling. At times when they are threatened or otherwise need to physically react, the sea lion can move at surprisingly fast speeds over short distances. The seal moves very differently without the advantage of rotating flippers. He pulls himself along with his front flippers, rolling and shuffling from side to side or by utilising some push from his rear flippers with a caterpillar like movement. This distinction gives the seal a much more cumbersome appearance when in motion.

As sea lions appear more at home on land than seals, certain species will spend longer periods on land and out of the water than many species of seal. As this is species specific however, it isn't a sure way to differentiate between seals and sea lions.

Another difference also concerns the flippers but is much less easily distinguishable unless the animal is being observed from a short distance. The front flippers of the seal are covered in short fur while those of the seal lion are hairless and with a much shorter nail.

The ears of the two animals offer another visual clue to their separate identities. Sea lions have an ear flap while seals have only an ear hole and no flap. The ear flaps are very small and not always clearly visible so again may be difficult to spot unless the observer is at close quarters.

Yet even harder to spot is the difference between the whiskers of the two animals. Sea lions have smooth whiskers and seals have a more crinkled appearance.

The last of the main differences is in relation to the way these marine mammals move once they are in the water and the utilisation of their flippers. Sea lions propel themselves by use of the front flippers while steering with the rear flippers. The action of the front flippers, if observed underwater, have some similarity with that of a bird flapping its wings. Seals use their front and rear flippers for directly opposite purposes so propulsion comes from the rear flippers while direction is the domain of the front flippers.

There are other small differences but these cannot be ascertained through casual observance, only through scientific or biological study.

There are 14 distinct species within the Otariidae family (sea lions and fur seals) and 18 within the Phocidae family (true seals) and where differences occur in habitat, diet and size, these are just as likely to be within the family as between the families. Thus seals and sea lions are found in many environments as diverse as polar regions, both northern and southern hemisphere and in equatorial regions.

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