60 groups and 1316 species, recorded across 15 destinations. Every group has a written introduction: what is in it, what separates the animals in it from each other, and where and when they are found. Start with a group, or go straight to the full index.
By family, under the name a diver would use rather than the one on the specimen jar. The last group is the residue, and it is watched: a group nobody would choose to filter by is not a group.
The fish that lives in an anemone and nowhere else.
Deep-bodied like butterflyfish and told apart by a single character: a spine at the lower corner of the gill cover, which angelfish have and butterflyfish do not.
Tall, flattened, silver-and-black fish that hang over wrecks and drop-offs in small groups.
Small bottom fish with a blunt head and, in many species, a fringe over the eyes.
Thin, deep-bodied and marked to break up the outline, usually in pairs that stay together for years.
Large-eyed fish that spend the day under a ledge, inside a sponge or among urchin spines, and feed in open water at night.
Small, abundant and the most territorial fish on the reef.
Small, bright, fast fish that live in a hole in the reef and are visible for about a second at a time.
Small bottom fish that walk on their pelvic fins over rubble rather than swimming.
The eels that are not morays: garden eels, snake eels, conger eels and the ribbon eel.
Flounders and soles, which start life symmetrical and swimming upright, then have one eye migrate across the head as they settle onto one side.
Anglerfish: ambush predators that sit still, look like sponge, rubble or weed, and fish for what passes with a modified first dorsal spine.
Named for a pair of chin barbels they use to taste the sand while probing it.
The largest family of marine fish and the one most divers walk past.
Groupers, hinds, coral groupers, soapfish and the anthias, which are small groupers despite looking like nothing of the kind.
Small predators that perch on coral, sponge or a gorgonian on thickened lower pectoral fin rays, and drop onto anything small that passes.
Fast open-water hunters that come in over the reef rather than living on it: trevallies, jacks, barracuda, mackerel, tuna and the amberjacks.
Fish that live head-up in a vertical burrow they dig and line themselves, and drop back into it tail first when anything comes close.
Lizardfish, sand divers and flatheads: bottom ambush predators that lie still on sand or bury with the eyes out, and take a passing fish from a standing start.
Eels that live in a hole with the head out, opening and closing the mouth to pump water over the gills.
Temperate bottom fish with thickened lower pectoral fin rays they prop themselves on.
Fused teeth that form a beak, used to scrape algae off dead coral.
Pufferfish, tobies, porcupinefish, boxfish and cowfish.
Algae grazers with a small mouth and, in most species, a habit of moving in pairs.
Venomous-spined fish that hold still and rely on not being seen.
Seahorses, pygmy seahorses, pipefish and pipehorses, together with the ghost pipefish, which belong to a different family but are found the same way.
A goby and a snapping shrimp sharing one burrow.
Snappers, grunts, sweetlips, emperors, breams and fusiliers.
Red fish with very large eyes, packed under ledges and in caves by day and out over the reef at night.
Grazers that keep algae off the reef, named for the hinged blade at the base of the tail.
Triggerfish and filefish, which swim by rippling the dorsal and anal fins rather than with the tail.
Long, thin, tubular fish that hunt by stealth rather than speed: the trumpetfish, which hangs among gorgonians, and the cornetfish, which hovers over open ground with a whip-like filament trailing off the tail.
The largest fish family on a reef and the one that changes most between juvenile, female and terminal male.
The fish that have nowhere else to go on this site: about thirty entries, from about twenty families, filed together because building a group for one or two species helps nobody.
The animals a dive is planned around rather than found on. Sharks and rays are fish and are separated out here anyway, because that is how anyone booking a trip thinks about them.
Most of what a muck dive is actually for. The last group is not a family but the residue, and it is watched the same way the fish one is.
Octopus, cuttlefish and squid, and most of the group is octopus.
Sea slugs: dorids, aeolids, headshield slugs, sap-suckers, sea hares and the side-gilled slugs.
The molluscs with a shell: sea snails, cowries, cones, conches, chitons and the bivalves.
Cleaner shrimps, snapping shrimps and the commensals.
Stomatopods: the smashers, which break shells with a club, and the spearers, which take fish with a barbed strike.
Crabs that are not hermit crabs: the decorators, the coral dwellers, the swimmers and the ones that spend the day buried.
Crabs that live in a shell they did not grow.
Spiny lobsters, slipper lobsters and the squat lobsters, which are not lobsters at all.
The crustaceans that live on another animal at its expense.
Amphipods: flattened crustaceans, mostly a few millimetres long, and normally seen as movement rather than as an animal.
Sea stars, from the cushion star to the crown-of-thorns.
Brittle stars and basket stars: five arms, a small central disc, and a habit of living under or inside something else.
Crinoids.
Sea urchins, including the two that carry venom and the two that live buried.
Sea cucumbers.
Polychaetes and the worm-shaped animals from several other phyla.
Polyclad flatworms.
Jellyfish, siphonophores and stinging hydroids.
Anemones, tube anemones, corallimorphs and zoanthids.
Less a group of animals than a group of structures.
Sea squirts and colonial ascidians.
What is left when every other group has taken what belongs to it: a comb jelly that crawls and a sea spider.
Blackwater diving is a drifting night dive in open water over deep ground, on a lit downline, looking at animals that rise towards the surface after dark with the vertical migration. The entries here are what a camera actually catches on those dives.
All 52 blackwater & plankton entries →60 of the 60 groups carry a written introduction. The rest have the counts, the species and the destinations, and the writing is being added.
