The Bluebell Tunicate (Clavelina Puertosecensis) pictured above can be found in the Caribbean and all around Utila. It has dense blue body with a white siphon rim.

We posed two questions for you to consider; Plant or animal? Backbone or cellulose?

A bit of a trick question - there isn't straightforward answer to this! In fact they have a bit of both and it turns out they have a quite a lot in common with us humans as well...

Actually an animal, tunicates are one of the most fascinating creatures of the reef. Neither vertebrate or invertebrate and on top of that most tunicates are hermaphrodites. The eggs are kept inside the body until they hatch, while sperm is released into the water where it can fertilize other individuals.

The tunicate begins life as a mobile tadpole. This larval stage has a lot in common with the embryos of vertebrates.  They have a primitive backbone called a notochord which in vertebrate embryos develops into the spinal column. It has a tail, gill slits, and primitive sensory organs.

In fact tunicates share about 80% of their genes with humans and they are used in human genome research . Recently it has been shown that tunicates can correct abnormalities in their bodies over a number of generations which suggest that a similar regenerative process may be possible in humans.

The larval stage is not capable of feeding and is a dispersal mechanism only. When it finds a suitable rock it will cement itself in place whereupon many physical changes will start to take place. Interestingly one of them is the digestion of the cerebral ganglion previously used to control movement - in other words the tunicate larvae eat their own brains!

Adults grow into a barrel shaped body which is supported by cellulose. The tunicate is the only animal to produce cellulose. In some ways the tunicate has more in common with bacteria, fungi and plants than with vertebrates.

The adult is a suspension feeder using it's barrel shaped body to siphon water to trap plankton (their primary food source). They have two openings; an incurrent siphon and an excurrent siphon.

Some tunicates species remain pelagic, swimming or drifting in the open sea.

The tunicate is only one of the creatures that inhabit the reefs and we have so much to learn from this one simple creature, especially in the fields of biology and healthcare.

If you are interested in finding out more about the other fascinating creatures, like the supposedly simply tunicate, that inhabit our reef how they reproduce, live, and the roles they play please ask us about our Naturalist Specialty conducted by our resident reef ecosystem expert.