coral

Cnidarians Known as Hydroids: Animals Looking Like Plants

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 […]

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 […]

There’s No Place Like Home

Like most divers I know, I thoroughly enjoy my dive trips to tropical destinations. After all, who doesn’t enjoy great visibility, warm water, colorful reefs and all of the associated marine life?  In the coming months, various photo assignments will have me diving off the Caribbean islands of Guadeloupe, Dominica and Grand Cayman. As you probably suspect, I am looking forward to all of these trips. But the dive trip that I am looking forward to the most in the coming months is an October […]

Bryozoans: Mother Nature’s Look-Alikes

Ever look at a horse and wonder if it was a pig or a cat? Me neither. I have however, looked at dozens of my photos and wondered if they were actually bryozoans and not the hydroids, corals or seaweeds they resembled.  Mother Nature turned trickster when she created bryozoans. She gave them many different forms and colors. On land, an animal that looks like a horse is very probably a horse. Underwater, an animal that looks like a hydroid, coral or seaweed may just […]

Pretty But Poorly Understood Polyps: Sea Anemones

Among the approximately 10,000 species that belong to the phylum Cnidaria (the ‚ “C” is silent), there are at least 100 that are dangerous to humans. The phylum name means “nettle” in Greek and its members include sea anemones, corals, sea pens, gorgonians, jellyfishes and hydroids. Most of them are carnivores and most have nematocysts, which are used for defense and catching food. Fortunately, sea anemones are not dangerous to humans; their tiny harpoons (nematocysts) cannot penetrate deep enough into our skin to deliver toxin […]

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