Crown-of-thorns Starfish (Acanthaster planci)
Image Copyright Jonathan Milnes
Observed: Koh Chang Reefs, December 2015
Observed By: Jonathan Milnes
The Crown-of-thorns starfish is a large 25-25cm wide starfish that is a voracious predator that feeds on corals.
It is named after the biblical crown of thorns since that is what its poisonous thorn-like spines resemble.
The crown-of-thorns has a few natural predators (although some species of triggerfish and snails feed on them) and so populations can grow to such high numbers that they can totally destroy coral reefs. So large numbers of crown-of-thorns seastar are a very bad thing for a coral reef and it is not uncommon for people to take action to control their numbers thus protecting the reef itself.
Crown-of-thorns Starfish Wikipedia
Image Copyright Jonathan Milnes
Image Copyright Jonathan Milnes
Black Sea Urchin (Diadema antillarum)
Image Copyright Jonathan Milnes
Observed: Koh Chang Reefs, December 2015
Observed By: Jonathan Milnes
Watch out for the sharp and brittle spines of the black sea urchin. A trailing hand or foot that brushes against them will cause them to break off in the flesh and despite having no poison they can easily cause infection and are the very devil to remove.
The black sea urchin, as you’d imagine has a black-coloured body and spines. It is massively widespread and is the most abundant herbivore on the coral reefs of Koh Chang.
Black Sea Urchin Wikipedia
Banded Sea Urchin (Echinotrix calamaris)
Image Copyright BB Divers
Observed: Koh Chang Reefs, December 2015
Observed By: BB Divers
Watch out for the sharp and brittle spines of the banded sea urchin. A trailing hand or foot that brushes against them will cause them to break off in the flesh and despite having no poison they can easily cause infection and are the very devil to remove.
The spines of the sea urchin radiate from a roundish shell that forms their endoskeleton and protects the urchin from predators. Like their close relatives the startfish sea urchins exhibit five fold symmetry with five equal-sized body parts radiating out from a central point.
Banded Sea Urchin Wikipedia
Indian Cushion Seastar (Culcita schmideliana)
Image Copyright 2010 jonathan Milnes
Observed: Koh Chang Reefs, February 2010
Observed By: Jonathan Milnes
The Indian Cushion Sea Star is a large and, you guessed it, cushion-like species of starfish found on Koh Chang. It has a a very different shape to the more typical five-armed examples of the starfish family but if you look closely you can still see the pentagonal shape of the animal.
Starfish are not, as many people think, members of the Mollusc family, they are in fact classified along with sea wasps, sea urchins and brittle stars as Echinoderms. I’d be lying if I said that I knew that when I started writing this.
Indian Cushion Seastar
