I think that starfish are a little gross. They have a bunch of tiny tubes for feet. Their mouths are hideous. They have five limbs and all of them look the same, which is stupid and confusing. Where’s the front? Where’s the back? Where’s their head? Where’s their torso?

Even people who actively study starfish and their equally-yucky relatives found this baffling, but for slightly different reasons. See, one of the largest questions with starfish lied in their body plan. Echinoderms like starfish have what’s called a pentaradial body plan, which means that they’re made up of five equal sections. 

This is radically different from the bilateral body plan, which is the same symmetrical body plan that all vertebrates and most invertebrates share. Most things have the bilateral body plan because of a series of similar genetic actions that can be traced in the main body regions (the head and torso).

The real kicker with sea stars is that they begin life as little larvae with bilateral body plans. It’s only later in life that they transition to the pentaradial plan, something that’s been befuddling researchers for quite a while. It was largely unclear how something goes from having the bilateral-standard head, trunk, and tail to…whatever echinoderms are doing.

But thanks to a recent study that tracked the expression of certain genes involved with forming body parts such as the head and torso, we now know what echinoderms are doing. 

Researchers found gene expressions involved in forming the head all over the bodies of sea stars, clustered in particular in the center of the creatures, with the expression for the trunk and tail almost entirely absent. This indicates that the latter two elements are absent in echinoderm body plans, and they’re essentially…heads with legs and arms.

They’re all pretty happy because as funny as it is, this is actually quite a big breakthrough for the study of echinoderms. It gives us a much better idea of how they’re related to other organisms and helps us trace their evolutionary ties.

Still, I believe that I can both acknowledge the advancement and also want to crawl out of skin due to this horrid new piece of information. Heads writhing around the ocean floor, that’s what starfish are. Don’t like that. Someone call Junji Ito, nature’s got a great idea for his next book.