Swimming sea cucumbers

It can be hard for many slow-moving animals that live on the seafloor to travel from place to place. Most sea cucumbers (holothurians) live a sedentary life on the bottom of the ocean, eating sediment or detritus that rains down from above. But some sea cucumbers temporarily leave the life of eating and pooping on the seafloor by swimming. They may do this as a defense behavior, or to find a mate. Sea cucumbers have made remarkable adaptations to master the challenges of living in the deep sea.

Giant sea spider hunches over a pom-pom anemone

Deep-sea pycnogonids can have long legs that grow to over 50 centimeters (20 inches) across.