Do Sea Squirts Really Eat Their Brains?
After the ability to squirt you in the eye, squirts are probably most famous for “eating their brains.” What happens isn’t quite as drastic as it sounds, but the sea squirt life-cycle is nonetheless “extreme” and fascinating.
Sea squirts are hermaphrodites—they have both male and female reproductive organs. They spawn by releasing eggs and sperm into the water at the same time. After about three days, eggs develop into tadpole-like larvae, just like their relatives the salps. They wiggle and twitch around, which helps disperse them.
Sea Squirt Larva
The free-swimming larvae stage lasts only a short time, since the larvae aren’t capable of feeding. Soon, they settle to the bottom and cement themselves headfirst to the spot where they will spend the rest of their lives. They need to start feeding, so an amazing transformation begins.
The sea squirt larvae begin absorbing all the tadpole-like parts that made them chordates. Where the sea squirt larva once had gills, it develops the intake and exist siphons that will help it bring water and food into its body. It absorbs its twitching tail. It absorbs its primitive eye and its spine-like notocord. Finally, it even absorbs the rudimentary little “brain” (cerebral ganglion) that it used to swim about and find its attachment place.
So, yes, in common parlance, the sea squirt “eats its own brain,” such as it is.
