Diadematoid echinoids: A cryptic part of the tropical fossil record

Stephen K Donovan (The Netherlands) The writers of holiday brochures invariably fail to mention, let alone emphasise, the bad points of a location. For example, I’ve lived in both Jamaica and the Netherlands, and, for me, the thing that unites these two countries is the number of mosquitoes. However, as mosquitoes aren’t a good sales point with tourists, they are carefully ignored in holiday brochures and advertisements. Another Caribbean critter that doesn’t get mentioned until you actually arrive and want to go for a dip in the sea is the sea urchin, known in Jamaica as a sea egg. In truth, any danger to the unwary swimmer comes from the few species of regular echinoid that have long, pointed spines. These are found in many shallow water habitats, but are best concealed (and, therefore, most dangerous to the swimmer) in seagrass beds. The best protection from these echinoids is to wear an old pair of training shoes that you’d be happy to dispose of at the end of the vacation. However, without prior knowledge, who would take such a thing on holiday with them? Among these echinoids, the one most likely to ruin your holiday is the black, long-spined urchin, Diadema antillarum (Phillipi) in the Caribbean; which is broadly similar in morphology to the figured specimen, Diadema setosum (Leske) from Indonesia (Fig. 1). These echinoids have relatively small bodies, but numerous long, needle-like spines. These are, essentially, single calcite crystals. The unsuspecting swimmer treading on such an urchin will have … Read More

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