Once again we dive into Cnidaria, a large phylum that contains approximately 10,000 species. Phylum members include many animals that attract attention because of their bright colors: sea anemones, corals, sea pens, gorgonians and jellyfish. These creatures can afford to flaunt their beauty because most of them have defensive polyps loaded with nematocysts (also called cnidocytes) that can fire venomous miniature harpoons. Lucky for us, most of these weapons are too tiny to penetrate our skin. Cnidarians currently belong to one of four classes: Anthozoa […]
gorgonians
Not Your Average Anemones: Examining Unusual Species
We’ve discussed cnidarians in this column several times and will likely do so many more. There are about 10,000 species in this phylum and since most of them live in the ocean, divers encounter them all the time. Many are photogenic, which is why my files are full of their images. The two forms of cnidarians, polyps and medusae, are, according to The Shape of Life, “essentially mirrors of each other.” Polyps (i.e., anemones) are attached to a surface on one end by the pedal […]
Admiring California Hydrocoral
Much prized by underwater photographers for its beautiful colors, California hydrocoral (Stylaster californicus) is one of the 350 species of hydroids in the Phylum Cnidaria. A close cousin of the fire corals found in tropical waters, it is not a true (stony) coral. Cnidaria (the “C” is silent) is not a small, insignificant phylum. It contains approximately 10,000 species, at least 100 of which are dangerous to humans. The phylum name means “nettle” in Greek and its members include some of the most photogenic animals […]
California’s Undersea Flower Animals: The Stony Corals
It’s a fact stranger than fiction: there are underwater creatures commonly found in the Pacific Ocean off the California coast that are biologically classified as “flower animals.” The class is Anthozoa, formed from two Greek words, anthos, meaning “flower” and zoa, meaning “animals,” and it contains the stony corals. Anthozoa is a class within the photogenic phylum Cnidaria (the “C” is silent), which means “nettle” in Greek. Besides corals, phylum members include sea anemones, sea pens, gorgonians, jellyfishes and hydroids. Cnidarians have two forms, polyps […]
