Pinnipeds: Decline of the Monk Seals

Mediterranean monk seal
(museum specimen)

The great majority of seal species are found in cold, often freezing waters. Even harbour and elephant seals, which are frequently found in temperate, or even subtropical, climes, also inhabit colder latitudes for at least part of the year. There are just three modern species of true seal that are found solely in warm waters, and they all happen to be closely related. These are the monk seals.

It's not actually known why these animals are called "monk" seals. The oldest known reference to the term comes from Johann Hermann in 1779, when he wrote the first scientific description of the Mediterranean monk seal (Monachus monachus), and gave it its scientific name. The only reason he gave for doing so was that he'd heard that the animal was called that in France, and thought that maybe that was because, seen from behind, the head and shoulders looked a bit like a robed and hooded man. But he was guessing about that latter part, and there doesn't seem to be any independent corroboration that the animal really was called a "monk seal" in France (or, indeed, anywhere else) prior to his naming of it. Presumably, he'd got the name from somewhere, but, for all we know, he might have misremembered the details.

The Last Seals of the Mediterranean

Sculpture

There are eighteen recognised species of "true" seal (that is, as opposed to fur seals, which are actually more closely related to sea lions). Three of these species are currently listed as endangered under the most widely recognised international standard for such things, the IUCN Red List. Compared with some other groups of animals - rhinos being a particularly obvious example - this isn't really all that bad. But it could, of course, be rather better.

One of the endangered seal species is the Caspian seal, found only in the isolated and land-locked sea of the same name. The other two are monk seals, with one species each in the Mediterranean and off the coast of Hawaii. Quite how two such closely related species ended up on opposite sides of the globe is something I've discussed in an earlier post, but for today, the key point is that there used to be three species of monk seal, and that the other one went extinct around 1952.

Given this, the threat to the two remaining species is surely far from hypothetical. There are thought to be a little over a thousand Hawaiian monk seals alive today, but, as confirmed in a recent species review, the most endangered seal species of all is the Mediterranean monk seal (Monachus monachus) - the only seal species to live in the sea for which it is named.

The Seals That Swam in Tuscany

Hawaiian monk seals

There are two species of monk seal alive in the world today. One (Monachus monachus) lives in the Mediterranean and adjacent parts of the eastern Atlantic, while the other (M. schauinslandi) lives in Hawaii. You probably don't need to be a world-class expert in geography to at least have some idea that these two places aren't exactly what you'd call close to one another.

Now, monk seals don't have have the same sort of problems when it comes to dispersal as lemurs and the like do. Given time, they can just swim across vast stretches of ocean, feeding on fish as they do so. The apparent puzzle of their wide separation is also reduced by the fact that there used to be a third species, living in the Caribbean, which sadly went extinct in the late 20th century. The Caribbean is about half way between the other two locations, and that helps rather more than you might think at first glance.