#722: Starfish

Starfish are echidnaderms, named for their star-like shape. About 1,500 species can be found worldwide, living on oceanbeds ranging from the frigid polar waters to the tropics. Starfish are predators, feeding on benthic invertebrates. The more primitive species swallow their prey whole, digesting it internally and ejecting out the inedible parts. Advanced species actually evert part of their stomach, forcing it into the bivalve prey, and digesting it from the inside-out, outside its body. In many species, gender is a fluid concept, with some being gendered, others simultaneous hermaphrodites and some being sequential hermaphrodites and changing gender as they age. Like many relatively sessile invertebrates, larvae are free-swimming. Their diet consists of phytoplankton. They are also able to reproduce asexually, by losing one of thier arms, which then sprouts into a new Starfish.

The Northern Pacific seastar (which I might have to draw instead of this one) has been introduced to Australian waters, where it is a voracious predator doing significant damage to the marine environment. It is ranked on the list of Invasive Pests.