Megacrabs

 

Megacrabs/Coconut Crabs: Descendants of coconut crab, they have diversified. Most live in the trees, but some are strict ground dwellers. They live in dens underground, where they sleep, do their molting (it takes a month), and have their young. Their young live in pools made by their mother, safe from aquatic predators. The mother has a special pouch for water during the period to refresh the water and feed it plankton and algae.

They range from sizes of 5 inches long with leg spans of 1.5 feet to 3 feet long with leg spans of 9 feet. They also range in diets as adults, but as larvae and adolescents they fill different niches.

The larvae feed on plankton and algae. When they first go on land they feed on fruit and rotting meat, and make their way up and get more specialized to their adult diet.

The ground crabs look a lot like today's coconut crab. The tree crabs have flexible legs to hang in the trees upside down (as they don't have anything to grasp it with besides the leg itself) and long eyestalks to have a wide range of vision. All tree crabs have strong pincers and while all carnivorous ground crabs have strong pincers too, the herbivorous ground crabs don't.

The tree crabs move in the trees by sliding their legs while hanging upside down, when they have to go to a new branch they grab on to the branch (hence their strong pincers), and if after they test it it's strong enough to hold them they "jump" to the branch (while still holding on) and continue going.

While they have a strong exoskeleton, they still have predators. Their only predators are carnivore primates and other predators at least twice as big as them. They are immune to the bite of most terrestrial octopi. They actually need the venom protection not to prevent being hunted, but to prevent fatal bites while hunting the terrestrial octopi.

Beaver Crabs

 

Beaver Crab/Coconut Crabs: A 2 foot long ground megacrab, they form family groups to protect their young. They form dams like beavers from their serrated pincers to form a pool to protect their planktonic young. Then they protect their young and family members while molting, so they only fill 1 ecological niche in their lifetime. The mothers still have pouches to refresh the water for plankton and algae.

They are omnivores, leaning more on the carnivore side. They feed on fallen fruits, leaves from a specific future plant, and meat ranging from terrestrial octopi, antechinus, insectivore mice, other large arthropods (since the oxygen levels way higher), and carcasses. Only the biggest carnivores won't give up a carcass from a beaver crab family because of their serrated pincers.