Purple Sea Urchin Metamorphosis Controlled by Histamine

Most people will know of histamine as the chemical reaction your body produces when having an allergic reaction. It’s a neuro-transmitter and humans always have some histamine in their bodies. More is produced from things like mosquito bites, bee stings, and things to which people are allergic, causing what is known as an allergic reaction.

Studies reported in biomedcentral.com’s journal show that histamine might mean something  much more to sea urchins, the studies show that the histamine present in their bodies inhibits their abilities to reach metamorphosis and settle .

The purple sea urchin in the study, also known as strongylocentrotus purpuratus, is a member of the echinoids. This class consists of sea urchins and sand dollars.

It’s been found that histamine plays a huge role in regulating the sea urchin’s process of reaching competence.  Competence for them is described as the state at which the larval stage is able to go through metamorphosis into adulthood. The metamorphosis will occur once two things have been satisfied. One, competence has been achieved, and two, a suitable settlement site has been located.

This is relevant due to the role histamine has been shown to play in the urchin’s ability to reach competence.  The doctor who led the research, Dr. Andreas Heyland explains “Histamine is very important in controlling purple sea urchin competence and metamorphosis. We found an extensive network of histamine containing neurons in the pre-metamorphic and metamorphic ally competent larvae which mature as the larvae develop. When we looked in detail at the effects of histamine we found that histamine seemed to inhibit programmed cell death (PCD), an essential process of the metamorphic transition. In our experiments we were able to induce PCD and arm resorption with antihistamines further indicating that histamine is playing a central function in the complex regulatory signaling network underlying competence and metamorphosis.”

To put it more simply, the histamine located in the complex system of neurons can stop programmed cell death (PCD) and arm resorption. These two actions are essential for competence and settling of the purple sea urchin. They also found when administering one type of antihistamine, blocking the urchin’s own histamine, the amount of purple sea urchins that settled rose.

This shows that histamine has and still does play a role in the way sea urchins have developed and still are developing. This offers some insight into exactly why sea urchins have developed and evolved as they have.