The "Upside Down" Colossus

anápoda haustus ( "Legs Up Gulper" )

A gargantuan ocean roomba that sweeps up calories

Physical Biometrics:

Leg Span: Up to ~ 30 feet / 9.14 meters

Length: Around ~25 feet / 7.52 meters

Weight / Mass: ~ around 700 - 900 pounds / 300 - 400 kg

Distribution and Environment:

Upper epipelagic zone, floats aimlessly along the very surface in its adult stage. Zoeal stages are planktonic and pelagic, Megalopa stage is the stage where the crab will occasionally be found at the sea floor but mostly scrambles to gather materials at the upper ocean areas.

Description:

They are the largest animal on Hoxia ( as of 11 million years P.D. ), and their gargantuan size is attributed to filter feeding. 

Their lifecycle begins as the eggs are carried by the female, and mostly released upon the small mound of gathered debris it clings on. Some eggs slip into the ocean. The Zoeal stages are usually found swimming alongside the female to pick off after her feeding, though disperse afterwards. 

Their megalopa and maturing stages of life usually consist of generalist omnivores that are free swimming, though most of them now searching for floating debris. 

On Hoxia, enormous amounts of plant life that are unable to decay (since tree rot bacteria doesn't exist) are washed to sea after inland flooding. Various floating wood fragments, as well as clumped up seaweed and any other vegetation can be then used by these juvenile crabs. They find their own and cling on to as much as they can. They can sometimes gather the first of their materials from their parents or other adults.

Their lives then consist of swimming around finding more debris to gather, as well as starting on their filter feeding.  This behaviour stems off of their ancestors, who already practiced covering themself with other objects for camouflage.

 Their small "microisland" mound also serves as their rite of passage. they often cling to them for protection as they make their adult maturation molts, having to use their powerful legs to quickly tear out of their old exoskeletons. They then spend the rest of their lives filter feeding. 

Their small bit of land poking above the ocean surface also occasionally serves as pit stopping points for the TwiSeraph to rest on their migrations.

Because the stress of pumping hemolymph upwards for their limbs against gravity can be problematic, they often sequentially unfurl their limbs via extension to let bloodflow better before resuming flexion.

Evolution / Anatomy:

 They have a strange bodyplan configuration adjusted for living at the surface of the ocean. A crab's back shields it from overhead attacks coming from above, whilst it itself is stationary on. Apparently the solution to no longer living in such an environment was to simply aim the carapace downwards, in order to protect from attacks coming from below. Its carapace is extremely biomineralized with calcium carbonate, and covered in spines.

Their first chelipeds, have an extremely mobile propodus that can rotate for them to point the dactylus of the claw up or down. They use these massive limbs to sweep in food. The teeth of their claws now integrate with epidermal / endocuticle hairs for 'baleen".

Their antennae and antennule pairs are modified with large bristly spines to catch incoming biomass and to manipulate their food.

They have 3 pairs of enormous pereopods ( legs ), with the dactylopodite ending in a curved "hook". They use this to cling on to their floating debris. These limbs are also covered in spines, and occasionally use them to bludgeon or push away predators that get too close, as they are strong enough to do so.

Their hind legs have been modified into enormous swimming paddles similar to other real world free swimming crabs, and use them to propel themselves along the sea in search of their next meal.

Known Descendants: 

( N / A, coming soon )