Pencil urchin is certainly one of the most curious and most characteristic species of Mediterranean urchins. Its common name derives from the shape of its thorns which resemble a classic pencil or “Lapis” as we say in Tuscany. However, these thorns are quite fragile as they are funny and when you meet them it is always better to be careful not to touch them to prevent them from coming off. Pencil urchin Stylocidaris affinis Riccio matita intotheblue.it
What is the evolutionary advantage of this strange shape is easily understood these large spines probably discourage predators such as octopuses and other cephalopods, the main hunters of sea urchins, making these strange sea urchins very widespread in our Mediterranean Sea and in other oceans.
Stylocidaris affinis (Philippi, 1845), commonly known as Pencil urchin, is an echinoderm of the Cidaridae family.
Spines very evident, thick, well spaced, as long as the diameter of the body, yellow to red in color, which can reach 5 centimeters.
It feeds on bryozoans, molluscs, foraminifera.
Distribution and habitat
Mediterranean Sea and Atlantic Ocean, on coralligenous or detrital bottoms, from about 30 meters deep (except for some locations, such as Pantelleria, Vulcano or in the caves of Alghero, where it is sometimes found even at surface levels) up to 1000 meters. It is possible to find the sea urchins along the docks of the ports, following the cleaning of the nets in which they often become entangled.