Mertribs

The Mertribs

Mertribs are a clade of secondarily aquatic tribbets, basal members of the canithere lineage that have returned to the sea as agile predators of fishes in the rich shallow oceans of Serina in the Pangeacene. Their three-toed hind leg has reverted into a fluked tail which pulses upwards and down like a whale's while the forearms have adapted into seven-fingered flippers used to steer. They are warm-blooded, active predators, but their return to the sea has resulted in the loss of most of their pelage, save for the bristle-like facial whiskers. Their ears are also substantially reduced, the pinnae almost absent, serving little use underwater. Mertribs have evolved valves in their nostrils and ear canals to keep out water and are capable of holding their breath for more than fifteen minutes - plentiful time to pursue their piscine prey under the surface and grab it in highly elongated, extensible jaws lined with needle-like teeth.

above: a lone mertrib swims through clear tropical waters in search of prey.

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Mertribs are present in all of Serina's oceans by the middle Pangeacene. The smallest species is not much larger than a sea otter, while the largest can weigh a thousand pounds. With few exceptions, they are mainly active hunters of fish, though some species specialize on molluscs and at least one on larger vertebrate prey, including its relatives. Though fully aquatic, mertribs still return to the shore to give birth. Because suitable breeding sites are fairly uncommon, birthing female mertribs are forced to share them, often in large numbers. As a result, they are among the most social canitheres, very tolerant of other individuals of their own species. The young, however, are among the most well-developed at birth and least dependent of all canitheres. Whereas most other species have litters of very dependent young, the mertrib has usually just one large offspring - twins are rare but not unheard of. After a few hours on the beach, gaining their strength, they follow their mothers into the sea and stay with them for just two to three weeks before going off on their own and hunting for themselves.

Male mertribs do not gather on the beaches with the females, as the female is not receptive to mating until at least a month after giving birth, by which time her young is independent. This is possibly an adaptation adopted to prevent infanticide (the male killing her offspring so as to immediately impregnate her again), as it also occurs in terrestrial canitheres. Because they cannot mate when the females gather on shore, nor assist in rearing the young, the males are thus highly nomadic and hold no sense of territory, dedicating their lives to traveling across the seas in search of receptive females. Where multiple males come across a single potential mate they will bicker and jostle with the largest usually gaining mating rights, but they do not engage in ritualized combat and males are not usually otherwise antagonistic to their peers, even traveling at times in loose groups which improve the chances of each individual finding and catching food - if a fish escapes one, it will likely run into the jaws of another. This social cooperation, though primitive, is among the most advanced of all canitheres, and it is probable that mertribs are the most intelligent representatives of their group.