This appears to be the case for sea spiders, according to a new study. The creatures pass oxygen to their extremities via their gut fluids, rather than the substance they have in lieu of blood called hemolymph. While it’s strange that sea spiders — whose bodies are dominated by long, spindly legs punctuated by a tiny head and trunk — take oxygen into their bodies through pores in their outer layer, "their guts are just bizarre," said the study’s lead author Art Woods, a professor of ecology and evolutionary biology at the University of Montana.