Preying on three-ways, sack-back worms, and tokorats, the tadpole crabs hunt primarily at night when they cannot be seen by larger predators, spending the day sleeping deep in the least accessible parts of the tangled weeds. At night, they stretch their long legs to feel for prey as they crawl through the weeds. When needed, they can also swim by means of a powerful tail.
Most organisms on Ectora undergo a gradual transformation in anatomy as they age, but few can be said to truly undergo metamorphosis. In contrast, tadpole crabs grow up to become frog crabs. To reduce competition, the adults feed during the day and mostly eat plankton or small swimming weeds that they capture in their comb-like claws. They lose their tail and instead rely on their flippered legs. These legs easily detach if caught.
During mating season, males will dance to catch the attention of females. If she is receptive, the male will pull off one of his own legs and offer it as a meal to fortify her for the ordeals of pregnancy. While she is distracted with her meal, the male will then fertilize her eggs. After a short gestation period, the female will lay her eggs inside a large clump of seaweed where they hatch immediately.
Flapper crabs are herbivores that swim by means of fins attached to leg joints or the sides of their leg segments. A few species also have fins attached to the main body. They are capable of swimming in any direction without turning the body. They hold their legs and bodies folded up in strange ways, often resembling just a clump of weeds.
A juice sucker with odd anatomy is the climbing fish. This diminutive false fish has five digestive tracts that begin in beaked mouths and end in anal cones. Both the beaks and the cones are used as legs for climbing through the weeds. Thus the ventral surface becomes the posterior and the dorsal surface becomes the anterior. The beaks often specialize in different activities for different parts of the weeds, such as stripping, chewing, or crushing. In most species, the foremost beak sits at the end of a long, jointed appendage used for wrapping around and grasping weeds. This beak is usually used only for drinking juices, which make up the bulk of the animal’s diet. In most species, the rearmost “legs” are also jointed enough to grasp weeds by working together. The larger species tend to be spiny and lightly armored while the smaller species tend to be soft and have very reduced bones.
Wider than they are long, ray crabs are highly flexible herbivorous crustaceans that only swim sideways by undulating their bodies (a few relatives in the reefs can also walk sideways on multiple rows of short legs). They often have reduced or absent legs, but have a separate set of feeding claws for each mouth. There are many genera, including stripe crabs (5 mouths), grazing crabs (9 mouths), and ribbon crabs (15 mouths). They can range from three centimeters long to fifteen meters long.