I spent the last few days diving a few sites in Bonaire. I'm still trying to work out how to attach my backup air source. While I was doing that, I took a few pictures.
Below is a picture of a bearded fireworm. It is a type of polychaete worm which is an annelid. Earthworms are annelids too and they get the name from their many rings (from Latin anellus=little ring). Annelids may be polychaetes instead of polychaetes being annelids -- the taxonomists have yet to agree. In any case, this worm is a polychaete because it has many fine bristles, these are chaetae (i.e., polychaete) on the parapodia (para = along side of; podia = feet) of its many segments. . The bristles are full of toxins that will irritate the skin....hence the name, fireworm. These worms often feed on coral polyps, but may eat a variety of things on the reef. Unlike many polychaetes on the reef, the fireworms wander around the reef actively feed during the day. Most other polychaetes hide in holes, filter feed (e.g., christmas tree worms) or wander around at night. There's actually a large Caribbean species of polychaete (3+ feet long!) called "The Thing" that wanders around the reef at night.
As I was gearing up for a dive at "Cliff," a passerby said that they saw three black sea horses along the reef at about 30ft. Even with that information, these critters are incredibly well camouflaged, but I lucked out and saw some black "algae" moving with the surge. It was a seahorse! Very exciting! This is the first sea horse that I've ever found. This is called a Longsnout or Slender seahorse (Hippocampus reidi).
Clearly Cnidarians with cnidocytes are some of my favorite critters. Below are a couple of anemones -- a giant anemone (Condylactis gigantea) and a branching anemone (Lebrunia danae). The giant anemone has a spotted cleaner shrimp in it. In the Indo-Pacific anemone fish(e.g., Nemo) are abundant and often clean other fish, but in the Caribbean there are mostly anemone shrimp performing that job.