The Bulbocula Class makes up the bulk of large animals on Odin’s surface. The articulate mouthparts of their ancestors have evolved into limbs whose primary purpose is locomotion. And they have adapted what were once sensory tendrils into feeding paraglossae. They are extremely diverse and live in a range of habitats, filling a great number of niches.
Members of the Order Thalassus are adapted to live their entire lives in the sea, and their life cycle consists of three stages: nymph, adult, and pod. All nymphs start out tiny and they swim tail-first with their paddle-like limbs angled forward; to feed they need to reverse direction so their mouthparts are facing forward. The nymphs grow and develop, eventually making the transition to swimming head-first and and fitting into their adult niches. Adults attract mates through scent, leaving a thick trail of pheromones behind them as their mating season approaches. Once one has mated, it swims to the seafloor and changes into a pod (adapted from the pupa stage of its land-living ancestors), and in this stage it produces eggs that remain inside the body. These eggs hatch and release nymphs within the pod, which feed on the metamorphic tissue of their parent before breaking free and making a mad dash for the surface to take their first breath.