Background:

Electromagnetic pulses that precede earthquakes, and the ensuing crust deformations and vibrations, have been associated with unusual animal behavior (UAB), most commonly in terrestrial species but also in certain marine species, chiefly in the Chordata phylum (e.g. fish, cetaceans).

Goals:

This study explored the occurrence of earthquake-related UAB in an entirely new marine phylum, the Echinodermata.

Methods:

Formal and informal surveys conducted by fishing vessels preand post-earthquake along the southern coast of Belize (Central America) were collated.

Results:

The first cases of post-earthquake UAB in echinoderms were documented. They involved thousands of individuals of the holothuroids Isostichopus badionotus and Holothuria mexicana spawning on May 29, 2009 and January 10, 2018. These rare accounts represent the first direct correlation between an earthquake and spawning activity, which occurred outside the normal spawning season and at an unusual time of day.

Conclusions:

While a growing number of reports indicate that many terrestrial and a smaller number of marine species can change their behavior before and during an earthquake, post-earthquake effects related to reproduction have apparently never been reported before in the animal kingdom. While underlying mechanisms remain unclear, holothuroid echinoderms may be reacting directly or indirectly to seismic activity, or the pressure change generated by it.