Science Visualized Animals

Some young sea spiders can regrow their rear ends

The creatures seem to lose the ability when they stop shedding skin as adults

A microscope image of an adult sea spider made a full recovery after its back half was amputated.

The adult sea spider (Pycnogonum litorale) in this microscope image made a full recovery after its back half was amputated, showing that arthropods can regrow more body parts than scientists realized.

G. Brenneis

By Erin Garcia de Jesús

No backside, no problem for some young sea spiders.

The creatures can regenerate nearly complete parts of their bottom halves — including muscles, reproductive organs and the anus — or make do without them, researchers report January 23 in Proceedings of the National Academy of Sciences.