Bristlebunnies
Bristlebunnies split from their ancestor. Their filter baits are calcified, bundled, and attached to limb-like nubs. Those on the anal arm are used for propulsion, while those on the counter-arms retain their ancestral purpose of capturing smaller organisms to consume. They fill a niche not unlike that of brine shrimp or small krill, being tiny planktonic filter-feeders. They have green iron-based blood, making use of Chlorocruorin as their blood pigment, and they have developed a pair of light-sensitive patches of skin which they use to detect the time of day and potential predators. Unlike their ancestor, they are externally bilateral as well, with their counter-arms being smaller than their anal arm.
The entirety of the Bristlebunnies’ counter-arms are chemoreceptive, allowing for easy detection of potential food. The anal arm also has a tail extending past the anus, which is similarly chemoreceptive but specializes mainly in detecting pheromones. Like their ancestor, they are broadcast spawners. Gametes are released from openings in their “armpits”—behind their limb-nubs on the anal arm, in front of them on the counter-arms. They are also capable of asexual reproduction through binary fission much like a Terran flatworm.
As small fauna, Bristlebunnies speciate readily and there are far too many species to individually describe. Some species have very high tolerance to salinity and can thrive in brine pools. They are uncommon in polar regions, but some polar species do exist; these usually go dormant during the cold dark winters, mainly being active in the summer.