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Description
Symbiocrabs
Size: Varies by species, smallest are a few centimeters, largest can be more than 10 feet across
Ancestor: Squat Lobsters (Kiwaidae)
Species: Over 60

Kiwaidae Crabs did fairly well surviving the mass extinction, keeping their roles as scavengers for the most part. However, fierce competition led to many lineages going extinct. The most successful were oddball species that incorporated other, normally sessile organisms as symbiotes. The first just used anenomes, but soon other varients came to using sea lilies, sponges, and hydra. Symbiocrabs are all descended from squat lobsters, but are a non-monophyletic group, with several ancestors from several species.

Over the 100 million year absence of sun, many crab species began to incorporate their symbiotes into their life cycles. Polyps or larvae were scattered across their eggs by the mother crab, in the hope they will bond to the unborn crustaceans. Over time this they became so common nearly all living crabs have some kind of protection, food service, or hunting aid riding on their back. Any non-symbiotic crabs, even those that remained scavengers instead of branching out into new niches, became extinct during the freeze. Symbiocrabs were simply too successful, almost always having the edge. Some have even blended their digestive tracts to those of their symbiotes, so food is transfered from crab to cargo or vice versa. This had led to more “open” exoskeletons, to better allow their hosts to attach. This culminates in many features, like more strange growth to increase surface area, and porus holes that allow smaller corals and anemones to latch onto. Even blood capillaries have started to intertwine, allowing diffusion of energy from crab to host.

With so many species, there are several ones specialized to specific hosts. Shown is a generalist species, that employs many different hosts. Anemone’s are the most popular variant, due to the added protection from stinging nematocysts. Around 10 species of coral managed to survive the extinction event soley because of Symbiocrabs. Like the anemone’s, they offer protection and share food with the host. Some sponges have begun to grow on Symbiocrabs, and while not inherently beneficial, they offer added armor against predation. Finally, parasitic hydras take advantage of the Symbiocrabs open carry lifestyle and hitch a ride, catching copepods and other smaller crustaceans. Some fishrimp have even joined the family, one species immune to anemone stings that lives in the tentacles as the larger crab walks along.

Symbiocrabs occupy many niches, mostly as grazers and scavengers, moving across the ocean floor in search of food. A few are predatory, though highly specialized.

Description
Symbiocrabs
Size: Varies by species, smallest are a few centimeters, largest can be more than 10 feet across
Ancestor: Squat Lobsters (Kiwaidae)
Species: Over 60

Kiwaidae Crabs did fairly well surviving the mass extinction, keeping their roles as scavengers for the most part. However, fierce competition led to many lineages going extinct. The most successful were oddball species that incorporated other, normally sessile organisms as symbiotes. The first just used anenomes, but soon other varients came to using sea lilies, sponges, and hydra. Symbiocrabs are all descended from squat lobsters, but are a non-monophyletic group, with several ancestors from several species.

Over the 100 million year absence of sun, many crab species began to incorporate their symbiotes into their life cycles. Polyps or larvae were scattered across their eggs by the mother crab, in the hope they will bond to the unborn crustaceans. Over time this they became so common nearly all living crabs have some kind of protection, food service, or hunting aid riding on their back. Any non-symbiotic crabs, even those that remained scavengers instead of branching out into new niches, became extinct during the freeze. Symbiocrabs were simply too successful, almost always having the edge. Some have even blended their digestive tracts to those of their symbiotes, so food is transfered from crab to cargo or vice versa. This had led to more “open” exoskeletons, to better allow their hosts to attach. This culminates in many features, like more strange growth to increase surface area, and porus holes that allow smaller corals and anemones to latch onto. Even blood capillaries have started to intertwine, allowing diffusion of energy from crab to host.

With so many species, there are several ones specialized to specific hosts. Shown is a generalist species, that employs many different hosts. Anemone’s are the most popular variant, due to the added protection from stinging nematocysts. Around 10 species of coral managed to survive the extinction event soley because of Symbiocrabs. Like the anemone’s, they offer protection and share food with the host. Some sponges have begun to grow on Symbiocrabs, and while not inherently beneficial, they offer added armor against predation. Finally, parasitic hydras take advantage of the Symbiocrabs open carry lifestyle and hitch a ride, catching copepods and other smaller crustaceans. Some fishrimp have even joined the family, one species immune to anemone stings that lives in the tentacles as the larger crab walks along.

Symbiocrabs occupy many niches, mostly as grazers and scavengers, moving across the ocean floor in search of food. A few are predatory, though highly specialized.