WARNING: The spines break off easily and cause painful splinter related problems. Footwear is essential if you intend wandering around in shallow water.
Common Name: Sea urchins
Scientific Names: Arbacia lixula and Paracentrotus lividus.
Description: Urchins ranging in size from 2-3cm as adults. Both of these species have a rather squashed globular shape. The spines cover the entire body and are short (0.5cm), but in Arbacia they are packed densely and much greater in number. Arbacia is jet black and Paracentrotus a great range of browns and purple hues.
Distinctive Features: Arbacia is jet black with very dense spines, whereas Paracentrotus comes in various dark browns and purples with rather less dense spines.
Abundance: They are often found in very dense patches (10-40/square metre) and are present at every site with rocky habitats.
Habitat & Behaviour: They often live in circular depressions in the softer rocks which have been eroded over many years by previous Urchin occupants. This gives them some protection from wave action and predators. They are nocturnal and will emerge and move around to feed at night.
Reaction to Snorkellers & Divers: They are very obvious to see and have no reaction to divers. Divers have been prone to break open urchins to attract fish, but if you really want to feed the fish simply take in some bread.
Maltese Names: Rizza ragel (Arbacia) and Rizza mara (Paracentrotus).
Other Notes: There are two species which are commonly seen, the black Urchin Arbacia lixula, and a rather more colourful Urchin Paracentrotus lividus.
These Urchins and Paracentrotus in particular are used to make the famous Sicilian dish with Urchins and spaghetti chi ricci which means that in many places with easy access to the water, Urchins are becoming increasingly scarce.
Text: Bob Earll
Photo: Russell & Gill Bennett
Video: Julia Jagoditsch