THE PINNIPEDS
Before we can move on to examine some sea serpent accounts, it may be wise to ask why we are looking at such an outlandish notion to explain at least some of them. For how, even within the wondrous artistry of nature, could such an unlikely creature such as a seal with a long neck, exist?
There are no pictures, no TV documentaries and there is no telling carcass.
So why not a plesiosaur? At least we know that such reptiles at one time did frolic in the world’s oceans and if alive today, would tally remarkably well with many eyewitness reports of so-called sea serpents.
Or would they?
The fact of the matter is, that some of the most clear and concise accounts of long necked sea serpents typically identify some very mammalian and seal like characteristics. There are for instance descriptions of fur, ears and even whiskers, something that no relict plesiosaur appears to have had. What is more, if we can accept these reports as genuine observations, then it follows that other less descriptive accounts must relate to a similar type of animal.
Furthermore the only existing animals adapted to an aquatic environment that have fur, whiskers and may approach the size of apparent sea serpents seals and sea lions, which with the addition of a long necked family member would at least mimic such reported creatures.
Unfortunately at present all the evidence for this notion is circumstantial. Therefore any case we can hope to build can only be theoretical and speculative in nature and to theorise and speculate, we must first take a look at the group of animals that such a creature would represent, the pinnipeds or seals.
The term pinniped, or `fin` or `feather footed`, is used to describe a group of amphibious, mammalian, aquatic carnivores that all share similarities in body shape, ecology and behaviour. Although further subdivisions can be made, they are usually divided into three main families, the Phocidae (true seals), the Otariidae (fur seals and sea lions), and the Odobenidae (walrus).
At present there are two main theories of pinniped evolution.
The first, a monophyletic view, holds that all pinnipeds derived from a common, bear like ancestor in the late Oligocene or early Miocene (25 million years ago), with a subsequent divergence into the presently known families. The second, diphyletic view, is that phocids and otariids originated independently of each other some 20 million years ago, the otariidae and odobenidae evolving from a bear like ancestor and the phocidae from otter like animals in the mid Miocene. However, with the advent of modern genetic testing, studies have shown that at a molecular level at least, phocids and otariids resemble each other more closely than any other carnivores, thus implying the monophyletic view.
The ancestors of modern pinnipeds, the pinnipedimorphs , first appeared 25-27 million years ago and although primitive they can easily be identified as being the fore runners of modern day pinnipeds sharing the same basic shape and ecology of today’s species.
It is generally thought that the fossil record of pinnipeds reveals only a small fraction of what was once a greater diversity among the order and there are many palaentological gaps especially within the otariidae. It is thought that all existing otariids have evolved in the last 2-3 million years while the differentiation between the phocids and otariids has occurred in the last 2-5 million years.
Despite this possibility of common ancestry, there are still some distinct differences between the modern families, some of which are summarised below.
The Phocidae
Phocid seals are sometimes referred to as `earless seals`, as they lack noticeable external ears, (although some grey seals may in fact grow small external ear pinnae). Instead they have two openings into the ear canal, situated behind their eyes.
Crabeater Seal (M. Cameron) National Marine Mammal Laboratory
Their fore flippers are short while their hind ones are longer, and all of the flippers are clawed.
When swimming, phocids use a `sculling` action of their hindquarters and hind flippers, the fore flippers being used to steer at slow speeds. On land they move awkwardly, the hind flippers useless for
locomotion and although some species may pull themselves along using their fore flippers, they tend to lurch or bounce ungracefully and clumsily along the ground.
Reproductive behaviour in phocids varies, but compared to the other two families they have a shorter period of pup weaning and dependency. Because of this and their poor locomotion on land, phocids are usually considered to be the most advanced of the pinnipeds, gradually evolving to a purely aquatic existence in the same way that dolphins and whales must have done.
On the whole they tend to be larger than otariids and more streamlined. They are able to dive deeper and longer than the other two families.
Stellers
Sea Lions (NMML).
Otariid seals are also known as `eared seals` as they do possess two small, clipped looking ears.
Their fore flippers are long and have splayed digits, the first digit being longer and stronger than the rest. They have small nails situated well away from the flipper edge and these are also present in their hind flippers, along with further rudimentary claws on digits one and five.
Their waterproof pelage is generally thicker than phocids and they tend to have less blubber.
In the water otariids extend their head and neck for steering and swim with a strong, breaststroke action, the hind flippers being used as stabilisers. On land, they can rotate their hind flippers forward, using them to walk or bound, lifting their bodies clear of the ground. At the same time they swing their head and neck from side to side creating momentum for their movement.
All otariids share the same polygamous reproductive behaviour to a certain extent and compared to phocids, they have a longer pup weaning and pup dependency period.Although sexual dimorphism is present in both otariids and phocids, it is usually more pronounced and striking in otariids. For instance mature male fur seals have visible ruffled manes.
The odobenids are unusual, (as any picture will show), in the fact that although they form a separate family order, they share both phocid and otariid characteristics.
Like phocids, they do not possess obvious external ears while like otariids they can use their hind flippers for locomotion on land. When they swim, they use a mixture of both phocid and otariid technique. At one time they were thought to be more closely related to the otariids but are now thought to be closer to the phocids.
All in all, they are a bit of an odd mix.
The odobenids of course, also have a unique attribute of their own and one that is not found in the other two families, their tusks. These unwieldy assets are used primarily in sexual display and for hauling onto and digging into the ice as well as feeding. Although present today, fossil odobenids do not appear to have had them. Fossil evidence has also indicated that in the past there were around thirteen different species and early walruses called dusignathines, resembled sea lions.
Of all the pinnipeds, they have the longest pup weaning and dependency, and are also the slowest swimmers.
There are thought to be some 50 million pinnipeds in existence today, 90 percent being phocid, the remaining ten percent otariids and odobenids.
It is thought that phocids first appeared in the North Atlantic about 15 million years ago, their ancestors having migrated through The Central American Seaway, and following deteriorating climatic conditions it is thought that they migrated both north and south.
The otariids first appear in the North Pacific, approximately 10 million years ago, from where they migrated southwards, either through The Central American Seaway, or along the coast of South America (or both), with the sea lion family diverging about 3 million years ago to form a separate family.
The Odobenids first appeared in the North Pacific 5-8 million years ago, where it is thought that they migrated first into the North Atlantic before returning to the Pacific via the Arctic.
Today, some species such as the Guadalupe fur seal and Mediterranean monk seal are confined to specific areas, while species such as the elephant seals, occupy large ranges in both hemispheres.
Most pinnipeds tend to migrate and wander widely from their habitats, sometimes travelling vast distances and many species overlap each other in their distribution patterns. Walruses are found in both the North Atlantic and North Pacific Arctic regions while most fur seals are found in the southern hemisphere. Sea lions are found in both.
No otariid species inhabits the extreme Polar Regions or North Atlantic, while no species of pinniped is native to the Indian Ocean.
During their evolution pinnipeds have become well adapted to their particular ecological niche and in recent years, with the outlawing of massive seal culls, many species have begun to increase in number and recover from previous depletion. They are intelligent, efficient and versatile animals able to adapt various strategies for survival sometimes in some very inhospitable conditions. Life expectancy on average can be 20-30 years although the oldest pinniped in the world, (documented from the Shetland Isles), made the ripe old age of 46. 1
Some species such as the baikal seal a lake living pinniped from Russia have adapted a freshwater environment to live in although all pinnipeds can live in both fresh and marine water.
As well as being tremendous swimmers, pinnipeds are also able to dive to great depths, sometimes for quite considerable periods of time. Some like the Weddell seal have been recorded to dive for over an hour (one recorded dive took 73minutes). How pinnipeds manage this capability is still something of a mystery.
It is not thought that they use echolocation as some cetaceans do, but there is strong evidence to suggest that they use a similar sound locating method.
Most pinnipeds usually exhibit playful, non-aggressive behaviour and can be shy. Being mammals they are often also curious in their nature. Most are sociable interacting well with others of their species and in certain cases, such as the Californian sea lion, humans as well.
There are of course exceptions to this rule as the following pages will show and the publics perception of the behaviour and appearance of pinnipeds tends to be shaped by their knowledge of familiar seals observed through various popular mediums. Such demeanour is lacking in some species such as the unpredictable leopard seal while others like the Mediterranean monk seal are extremely private and reclusive creatures, deliberately shying away from human attention.
Despite their many adaptions, present day pinnipeds, unlike the ceteceans have not evolved away from their need to rely on land for certain stages of their lives and all presently known pinnipeds must return to land to give birth. Therefore, if a long necked variant exists, it must have a similar need, further implying that if it did exist, it would have been noticed somewhere by now.
Well as the following pages will show, maybe it has.
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