Speculative Biology Sunday: Greater Trygen

4 Oct

The Greater Trygen is one the largest species of the amphibious descendants of the Potamotrygonid freshwater rays of the modern day.

What were once the gill slits have completely closed up, all breathing is done through the spiracles behind the eyes. The gill arches are reinforced creating essentially book lungs capable of breathing air, but unfortunately means it is incapable of breathing air. They are capable of some vocalisations, mostly buzzing but they’re also capable of whistling.

Their pectoral fins are separated into several paddle like fins, two cephalic lobes and five smaller feeding appendages. All end in large claws derived from dermal denticles which are constantly being replaced as they wear down. The claws on the cephalic lobe are serrated. Their main weapons for dispatching their prey though are the tail stings they inherited from their modern ancestors.
They are surprisingly strong besides durable for their size. Unlike modern elasmobranchs (sharks and rays) they have a ribcage derived from the pectoral girdle and basibranchial element and is “upside down” compared to tetrapods with the “ribs” not attaching directly to the notochord.
Like most elasmobranchs, they don’t rely soly on their internal skeleton for muscular attatchment. Their skin is made of a thick corset of criss-crossed collagen fibers to which a great deal of muscles involved in movement attach, making them quite powerful for their size and also forming protective armour along with their covering of tiny tooth-like dermal denticles.

Trygens are a lot more social compared modern elasmobranchs and hunt in small groups, usually five or six. These hunting groups consist of a central mating pair and satellite individuals. These satellite individuals can be the young of the mating pair that haven’t moved on yet, or unrelated young adults moving from group to group looking for their own mate. Their hunting strategies usually consist of an ambush prey items coming down for a drink, or exploding out of the undergrowth sheparding the prey item into the water where they are a lot maneuverable. The satellite individuals usually do most of the work with the mating pair coming in for the kill. Only one will ever attack with the poison stinger and this duty is passed around, and only ever used when the kill is a sure thing. This is to conserve their precious venom.
Young are born live in litters of two or three and stay with their parental group until they reach a certain size, as opposed to a certain age.

Very few of the terrestrial or arboreal predators of the South American rainforests will ever agitate a pack of Greater Trygens, though each group is usually constantly tailed by a carrion specialist of one kind or another.



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