Seaguanas

As strange and wonderful animals have evolved on the land in the Pangeacene, so too have the seas been met with a breathtaking new diversity of species, as many groups of land-lubbing animals return to their roots in the oceans. Among them are the tribtiles, the basal grade of tribbets - reptile-like animals, similar to those from which the warm-blooded tribbetheres evolved.

Not all tribbets have gone in the direction of the new and successful tribbetheres. For there are many routes to success in the long, winding road of life. And for the seaguana, a tribtile which has become a marine herbivore in the abundant coastal reefs of the new age, that path has meant transforming into something truly special: it has become another sort of tribbet mermaid, mirroring the canitheres which have also done so, and transforming their hind leg into a wide, paddle-like fin.

Seaguanas are ectotherms - that is to say, they cannot maintain a body temperature higher than their surroundings as can the canitheres, tribbats, or molodonts which now share their world. But much of the world, now, is tropical - and these are warm, calm seas, which even assist in maintaining body heat, rather than stealing it. So their lack of a hot-blooded metabolism is no hindrance - rather, it allows them to get by on less food. And so, more of them can live in any one place than could warm-blooded grazers of their same size. Their habitat is snail reefs, coastal congregations of sessile molluscs which filter feed as waves bring detritus over them and over time link their shells into cement-like accretions that can cover whole coastal shelves. In warm seas like these, productivity is low in open waters, but here wave action stirs up the sediment continuously, upwelling nutrients which support diverse ecosystems. And so here, feeding on one of the lowest-level members of this food chain - single-celled algae clinging to these stony reefs - the seaguana can now be found in herds of many millions.  

In many ways, these tribbets are similar to the ancestor of the pangeacene mucks, which also fed on marine algae. They are better-suited for this role now, however, for they birth live young, and so do not have to compete for scarce nesting sites above the waves - and so as those mucks now lay claim to the land, the seaguanas take their old place at sea. With blunt, scraping jaws lined with many hundreds of tiny, easily-replaced teeth, they graze for much of each day below the water, swimming leisurely with their tails with their arms held close to their sides. Eyes set high on the skull let them peer above the water for danger without exposing themselves, and when predators threaten those hauled out on land to rest and bask in the sun launch themselves quickly into the sea, diving and scattering; they can hold their breath for 20 minutes or more, waiting out the danger while pressed into cracks and crevices on the coastal sea floor. Males are brightly decorated in hues of blue, gold and orange, and they compete for mates whilst hauled on land, flashing vibrant dorsal sails and emitting throaty bellows at rivals; the strongest and best-colored eventually claim small territories in which several females will join him. The females are subdued, with mossy grey-green hides that blend into the surrounding rocks as they rest. Each female will bear up to ten small but fully independent young in each litter, and may have three or rarely four each year, on account of the consistent warmth and food here in the tropics. Young are defended by their father at least for a few months, but once young males begin to show colors they are quickly driven far from their natal home, forming bands of similarly-aged males until one day they may be able to fight another adult for territory, and reproduce themselves.