Erizo huevo, cabeza de viejo, dentro del Parque Nacional Arrecifes de Xcalak
Sea urchins or urchins, archaically called sea hedgehogs, are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum.
Caught locally, held in tank.
Ultra-teeny, only about 1 mm. Nice find Marisa!
Estrella de bradley observada en la Ensenada El Embudo, en la Isla Espíritu Santo.
Here is a 2" Strongylocentrotus droebachiensis or Green Sea Urchin, found under a rock during the low tide.
Here is one of only three Pisaster ochraceus or Purple (aka Ochre) Stars I found today, in an area that used to have hundreds prior to the outbreak of Sea Star Wasting Syndrome. It was about 10" across, under a foot of water at low tide, and appeared very healthy. The white marks are caused by the reflection of sunlight through the water.
Echinoderms (Phylum Echinodermata from Greek, ἐχῖνος, echinos – "hedgehog" und δέρμα, derma – "skin") are a phylum of marine animals. The adults are recognizable by their (usually five-point) radial symmetry, and include such well-known animals as starfish, sea urchins, sand dollars, and sea cucumbers. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes (a superphylum), after...