Family of the Week: Paddle-Finned Sea Monkeys

 I realize this is late. I was so excited going to the bird expo last weekend, this blog slipped my mind. But I am back now.

The family Pinnepitheciidae is the earliest branch of completely aquatic pentadactyls. They arose from the family Promonsamiidae, particularly from the genus Hydrabilis, which is also the precursor of Thaladapis. These sea monkeys differ from the Delphinadapids by having larger, more rounded flippers, and a relatively shorter, spade-shaped tail. But like all other aquatic pentadactyls, these animals are just as agile in the water as other lemurs are in the trees. But unlike such aquatic lemurs as the Promonsamiids, these lemurs are almost entirely aquatic, only coming ashore on the beach to sleep and rear young. They breed in colonies, like sea lions. Their movement is not like that of sea lions, but more like sea turtles. They push themselves over the sand using all four flippers. The fur is short, but thick, like a bear's coat. All species are mostly active in the day time, until the breeding season, then they can become active at any hour, sustaining themselves with short naps every couple hours.

The largest species is Ichthyolemur, which measures around 25 feet long from head to tail, and weighs about 5 tons. As large as these animals are, the main source of food is krill. Occasionally they may feed on small, schooling fish like sardines. These are large animals, but the teeth are rather small, which is why they only feed on small prey. During the breeding season, the male Ichthyolemur goes through a dramatic change. The head and neck swell to twice the normal size, the skin toughens up around the head and neck as well, making an almost impenetrable mask, making their mating battles less bleeding. The fur gets very thick as well, as further protection from attacks by other males. Females are less protected, but mating battles between males and females is not as violent as it is between males and other males. 

The smallest species in the family is Bagaenhydra, which is roughly about 4 feet long, and weighs about 250 pounds. They are also among the fastest in this family, and are the only species of pinnepithiciid that is social even outside the breeding season. Their groups are rather tight-knit. Their main diet consists of small fish and krill. Like other members of this family, these animals are not deep divers, and spend most of their time in shallower water, rarely swimming in water that is more than 300 feet deep. 

Though these lemurs are primarily carnivorous, they are also prey for several other ocean inhabitants. Sea genets (both Haliophonia and Oceictis) are among their greatest threats in the ocean. The young may be taken by seals, like Eufoedes. On land, the deinognathids can very well snatch them up. In South African province, Spathodon can specialize in hunting sea monkeys that are on the beach to nap. Dogs, large viverrids and even the larger barofelids may take sick or young individuals. But these lemurs are not cowards. Though they prefer to take to the water when they feel threatened, they can also inflict serious harm to almost any attacking predators, and females are thus very protective of their young.

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