Tree of Life
Every animal in our guide, placed on the animal family tree. The closer two animals sit, the more recently they shared an ancestor: all the tangs share one twig, while gobies and clownfish grow from neighbouring branches of the same big fish limb.
- Fish 49
- Corals & anemones 20
- Other invertebrates 26
Outline tap a branch to open it
Kingdom Animalia Animals 95
Animals are living things made of many cells that must eat food to live. Fish, corals, crabs, snails and sea stars are all animals.
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Phylum Arthropoda Arthropods 10
Arthropods have jointed legs and a hard outer shell called an exoskeleton. To grow, they must crawl out of the old shell, which is called molting.
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Subphylum Crustacea Crustaceans 10
Crustaceans are arthropods with a hard shell and two pairs of feelers. Most live in water, like crabs, shrimps and lobsters.
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Class Malacostraca Malacostracans 10
This big class of crustaceans includes crabs, shrimps, lobsters and krill. Their bodies are built from about the same number of segments. Part of Multicrustacea
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Order Decapoda Decapods 10
Decapod means 'ten feet'. Crabs, shrimps, lobsters and hermit crabs all have ten legs, counting their claws. Part of Eumalacostraca › Eucarida
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Suborder Pleocyemata Egg-carrying decapods 10
In this group, the mother carries her eggs stuck under her tail until they hatch. It includes crabs, lobsters, hermit crabs and most shrimps.
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Superfamily Alpheoidea Snapping, cleaner and anemone shrimps 4
This group of shrimps includes snapping shrimps, cleaner shrimps and tiny anemone shrimps. Many live closely with other animals. Part of Caridea
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Family Lysmatidae Cleaner and peppermint shrimps 3
These shrimps often have long white feelers. Some clean other fish, and others eat pest anemones in aquariums.
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Genus Lysmata Cleaner shrimps 3
Lysmata shrimps include cleaner, fire and peppermint shrimps. Many start life as males and later become male and female at once.
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Family Thoridae Thorid shrimps 1
This family has small shrimps, and some of them live among sea anemones and corals.
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Genus Thor Sexy shrimps 1
Thor shrimps are tiny shrimps that live among sea anemones. The sexy shrimp wiggles its tail in the air.
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Family Diogenidae Left-handed hermit crabs 1
In many of these hermit crabs, the left claw is bigger than the right. They live in empty snail shells. Part of Anomura › Paguroidea
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Genus Clibanarius Clibanarius hermit crabs 1
These hermit crabs have two claws of about the same size. Most live in shallow, warm water near the shore.
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Superfamily Majoidea spider crabs 5
Part of Brachyura › Eubrachyura › Heterotremata
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Family Epialtidae 1
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Family Inachoididae 1
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Family Mithracidae Mithracid spider crabs 3
These spider crabs mostly live on reefs in warm seas. Many hide in rocks by day and come out at night.
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Genus Mithraculus Clinging crabs 2
Clinging crabs are small crabs that hold tightly onto rocks. The green emerald crab belongs here.
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Genus Pitho 1
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Phylum Chordata Chordates 49
Chordates have a stiff rod running down their back at some point in their lives. In fish and people, this rod is replaced by a backbone.
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Subphylum Vertebrata Vertebrates 49
Vertebrates are animals with a backbone and a skull. Fish, frogs, birds and people are all vertebrates.
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Class Teleostei Teleost fishes 49
Teleosts are bony fishes with thin, bendy fin rays and jaws that can push forward. Almost all of the fish in the world are teleosts. Part of Gnathostomata › Osteichthyes › Actinopterygii › Actinopteri
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Order Acanthuriformes Surgeonfishes, angelfishes and kin 14
This order of fishes includes surgeonfishes, marine angelfishes and rabbitfishes. Many have deep, flat bodies and graze on reefs.
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Family Acanthuridae Surgeonfishes and tangs 7
Surgeonfishes have a sharp spine, like a tiny knife, on each side of the tail. Most graze on algae on reefs.
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Genus Acanthurus Acanthurus surgeonfishes 4
This is the biggest group of surgeonfishes, with sharp tail spines. The powder blue tang belongs here.
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Genus Ctenochaetus Bristletooth tangs 1
Bristletooth tangs have bendy, comb-like teeth. They brush algae and bits of food off rocks and sand.
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Genus Paracanthurus Palette tangs 1
There is only one kind of fish in this group: the blue tang, with its royal blue body and yellow tail.
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Genus Zebrasoma Sailfin tangs 1
Sailfin tangs have tall fins on their back and belly that they can raise like sails. They graze on algae.
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Family Chaetodontidae Butterflyfishes 2
Butterflyfishes are flat, colorful reef fish with small, pointy mouths. Many have a dark stripe over each eye, and lots of them eat coral.
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Family Pomacanthidae Marine angelfishes 4
Marine angelfishes are colorful reef fish with a strong spine on each cheek. Many change their colors as they grow up.
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Genus Centropyge Pygmy angelfishes 4
Pygmy angelfishes are small, colorful angelfish that stay close to the reef. They graze on algae and tiny animals.
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Family Siganidae Rabbitfishes 1
Rabbitfishes nibble algae like rabbits nibble grass. Their fin spines have venom that can sting.
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Genus Siganus Rabbitfishes 1
Siganus is the main group of rabbitfishes, including the foxface. They eat algae and have venomous fin spines.
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Order Apogoniformes Cardinalfishes and nurseryfishes 2
In this order of fishes, the parents carry their eggs. Male cardinalfish hold the eggs in their mouths until they hatch.
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Family Apogonidae Cardinalfishes 2
Cardinalfishes are small fish with big eyes that are most active at night. The males carry the eggs in their mouths.
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Subfamily Apogoninae Typical cardinalfishes 2
This is the largest group of cardinalfishes. Like their relatives, the males carry the eggs in their mouths.
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Genus Pterapogon Banggai cardinalfishes 1
These cardinalfish have tall fins and white spots. The males carry the eggs and babies in their mouths.
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Genus Sphaeramia Pajama cardinalfishes 1
These cardinalfish have round bodies and big eyes. The pajama cardinal looks like it is wearing striped pajamas.
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Order Batrachoidiformes Toadfishes 1
This order has only one family, the toadfishes. They are chunky fish that sit on the bottom, and many males hum to call a mate.
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Family Batrachoididae Toadfishes 1
Toadfishes have wide, flat heads and huge mouths, a bit like toads. The males make humming or whistling sounds to call females to their nests.
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Order Blenniiformes Blennies and kin 4
This order includes blennies and their relatives. Most are small fish that perch on the bottom and peek out of holes.
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Family Blenniidae Combtooth blennies 4
Combtooth blennies are small fish with rows of comb-like teeth and no scales. Many scrape algae and peek out from holes in rock.
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Subfamily Salariinae Algae-scraping blennies 3
This big group of combtooth blennies includes many fish that scrape algae off rocks. Coral blennies and the lawnmower blenny belong here.
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Genus Ecsenius Coralblennies 2
Coralblennies are small blennies that perch on corals and rocks in the Indian and Pacific Oceans. They mostly graze on algae.
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Genus Salarias Lawnmower blennies 1
These blennies have many tiny teeth for scraping algae, like a lawnmower cutting grass.
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Order Callionymiformes Dragonets and kin 1
Dragonets are small, bottom-living fish with big heads and no scales. Many are very colorful, like the mandarin.
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Family Callionymidae Dragonets 1
Dragonets are small fish with big heads and slimy skin instead of scales. They hop along the bottom picking up tiny animals.
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Genus Synchiropus Synchiropus dragonets 1
These dragonets are small and slow and pick tiny animals off rocks and sand. The bright mandarin dragonet belongs here.
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Order Eupercaria (unplaced) Unplaced eupercarian fishes 11
Eupercaria is a huge group of fish with spiny fins. Scientists found it by studying DNA, and it holds wrasses, grunts, butterflyfishes and many more. 'Incertae sedis' means 'place not sure': scientists have not yet agreed which order wrasses belong in.
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Family Labridae Wrasses 9
Wrasses are a huge family of colorful fish that swim by flapping their front fins. Many change color, and some change from female to male.
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Genus Bodianus Hogfishes 2
Part of Hypsigenyinae › Clepticini
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Subfamily Cirrhilabrinae Fairy wrasses and allies 3
This group has many small, bright wrasses. Fairy wrasses swim above the reef to catch tiny floating food, and the six line wrasse belongs here too.
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Genus Cirrhilabrus Fairy wrasses 2
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Genus Pseudocheilinus Lined wrasses 1
These are small wrasses with stripes along their bodies, like the six line wrasse. They hunt tiny animals in the reef.
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Subfamily Julidinae Julidine wrasses 4
This is a big group of busy reef wrasses. Cleaner wrasses, bird wrasses, moon wrasses and the wrasses that sleep in the sand all belong here.
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Genus Gomphosus Bird wrasses 1
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Genus Halichoeres Halichoeres wrasses 1
This is a large group of wrasses that hunt small animals on reefs. Many bury themselves in sand to sleep at night.
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Genus Labroides Cleaner wrasses 1
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Genus Thalassoma 1
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Family Lutjanidae Snappers 2
Snappers are hunting fish with sharp teeth that often swim in schools near reefs. Many grow big and are caught for food.
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Genus Lutjanus 1
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Genus Macolor 1
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Order Gobiiformes Gobies and kin 4
This order includes gobies and sleepers. Most are small fish that live on the bottom, and many share burrows or perch on rocks.
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Family Gobiidae Gobies 4
Gobies are one of the biggest families of fish. Most are small and live on the bottom, and many share burrows with shrimp. Part of Gobioidei
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Subfamily Gobiinae True gobies 2
This huge group holds most gobies, including shrimp gobies and watchman gobies. Many have belly fins joined into a little suction cup for holding onto the bottom.
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Genus Amblyeleotris Shrimp gobies 1
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Genus Cryptocentrus Watchman gobies 1
Watchman gobies share a burrow with a pistol shrimp. The goby keeps watch while the nearly blind shrimp digs.
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Genus Nemateleotris Firefishes 2
Firefishes are slim, colorful fish with a tall front fin that they flick up and down. They dive into a burrow when scared. Part of Ptereleotrinae
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Order Ovalentaria (unplaced) Unplaced ovalentarian fishes 8
Ovalentaria is a big group of fish with spiny fins. Scientists found it by studying DNA, and most of its fish lay eggs that stay stuck to the bottom. 'Incertae sedis' means 'place not sure': scientists have not settled which order damselfishes, dottybacks and basslets belong in.
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Family Grammatidae Basslets 1
Basslets are small, brightly colored fish from the western Atlantic. They often hang upside down under ledges.
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Genus Gramma Grammas 1
Grammas are small, colorful basslets from the Caribbean. The royal gramma is purple in front and yellow at the back.
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Family Pomacentridae Damselfishes and clownfishes 6
Damselfishes are small, often colorful reef fish that guard their homes. Clownfish and chromis are damselfishes.
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Genus Amphiprion Clownfishes 3
Clownfish live among the stinging tentacles of sea anemones without getting hurt. They all start life as males, and the biggest can turn into a female.
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Genus Chromis Chromises 1
Chromis are small damselfish that swim in groups above the reef. They eat tiny animals floating in the water.
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Genus Dascyllus humbugs and dominos 2
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Family Pseudochromidae Dottybacks 1
Dottybacks are small, brightly colored fish that live in cracks in the reef. They can be bold and bossy for their size.
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Genus Pseudochromis Dottybacks 1
This is the main group of dottybacks. They are small, colorful fish that hide in rocks and guard their space. Part of Pseudochrominae
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Order Perciformes Perch-like fishes 2
These fish have sharp spines in the front part of the fin on their back. The name means 'perch-like', and this order holds perches, groupers and soapfishes.
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Suborder Percoidei 2
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Family Epinephelidae Groupers 1
Groupers are big-mouthed hunting fish that swallow their food whole. Most start life as girls, and some turn into boys when they grow big.
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Genus Cephalopholis Hinds 1
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Family Grammistidae Soapfishes 1
Soapfishes are cousins of the groupers with slimy, poisonous skin. The slime helps keep other fish from eating them.
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Genus Pogonoperca 1
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Order Syngnathiformes Pipefishes, seahorses and kin 1
These skinny fish have small, tube-shaped mouths and bony rings around their bodies. In many of them, the dads carry the eggs.
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Family Syngnathidae Pipefishes and seahorses 1
Pipefishes and seahorses have long snouts, armor plates and no belly fins. The males carry the eggs until the babies are born.
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Genus Doryrhamphus Flagtail pipefishes 1
Part of Nerophinae
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Order Tetraodontiformes Pufferfishes, triggerfishes and allies 1
This order holds puffers, triggerfish, filefish and boxfish. Many have strong teeth or beaks for crunching shells.
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Family Tetraodontidae Pufferfishes 1
Puffers can gulp water and blow up like a ball when they are scared. Their teeth are joined into a strong beak, and many have poison in their bodies. Part of Tetraodontoidei
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Genus Arothron Dogface puffers 1
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Phylum Cnidaria Cnidarians 20
Cnidarians are soft animals with tentacles. The tentacles have tiny stinging cells. Corals, sea anemones and jellyfish all belong here.
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Subphylum Anthozoa Corals and sea anemones 20
These cnidarians spend their whole lives as polyps: a tube with a mouth ringed by tentacles. Unlike jellyfish, they never swim around as a bell-shaped medusa.
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Class Hexacorallia Hexacorals 17
In this group the tentacles and body parts come in sixes or multiples of six. It includes stony corals, sea anemones, mushroom corals and zoanthids.
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Order Actiniaria Sea anemones 1
Sea anemones are single, soft polyps with no skeleton. They catch food with stinging tentacles, and some give clownfish a home.
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Family Actiniidae Actiniid sea anemones 1
This is the biggest family of sea anemones. Many have sticky bumps on their column, and the bubble-tip anemone belongs here. Part of Enthemonae › Actinioidea
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Genus Entacmaea Bubble-tip anemones 1
These sea anemones often have tentacles with bubble-shaped tips. Clownfish like to live in them.
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Order Corallimorpharia Mushroom corals 2
Mushroom corals, or corallimorphs, look like flat, soft discs. They are close cousins of stony corals but never build a hard skeleton.
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Family Discosomidae Disc mushroom corals 1
These mushroom corals form smooth, flat discs that stick to rocks. They come in many colors, and new discs can split off old ones.
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Genus Discosoma disc anemones 1
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Family Ricordeidae Ricordea mushrooms 1
These mushroom corals have bumpy discs. The bumps are short tentacles that look like little bubbles.
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Genus Ricordea Ricordea mushrooms 1
Ricordea are mushroom corals covered in tiny tentacles that look like bubbles. One kind lives in the Caribbean, and one lives in the Indian and Pacific Oceans.
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Order Scleractinia Stony corals 13
Stony corals build hard skeletons out of limestone under their soft polyps. Over many years, these skeletons pile up and make coral reefs.
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Suborder Refertina Complex corals 7
Complex corals are one of the two big branches of stony corals, found by studying their DNA. They usually have lighter, more porous skeletons than robust corals.
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Family Acroporidae Acroporid corals 2
This is the biggest family of stony corals and includes some of the fastest growers on the reef. Branching staghorns and plating Montipora belong here.
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Genus Montipora Pore corals 2
Montipora corals have tiny polyps sitting in little pores. They grow as plates, crusts or branches and come in many colors.
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Family Dendrophylliidae Dendrophylliid corals 1
This stony coral family includes Duncan corals, cup corals and orange sun corals. Many have big, colorful polyps, and some have no algae inside them.
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Genus Duncanopsammia Duncan corals 1
Duncan corals grow tubes topped with big, round polyps that look like little flowers. They are a popular, easy aquarium coral.
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Family Euphylliidae Euphylliid corals 4
These stony corals have long, fleshy polyps that stay out during the day. They include torch, hammer and frogspawn corals.
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Genus Euphyllia Torch corals 1
Euphyllia corals, such as torch corals, have long, flowing tentacles with round tips. They can sting corals that grow too close.
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Genus Fimbriaphyllia Hammer and frogspawn corals 3
These corals have fleshy tentacles shaped like hammers, anchors or bunches of eggs. Scientists split them from Euphyllia using DNA.
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Suborder Vacatina Robust corals 6
Robust corals are one of the two big branches of stony corals, found by studying their DNA. They usually build heavier, more solid skeletons than complex corals.
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Family Fungiidae mushroom corals 1
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Genus Fungia mushroom coral 1
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Family Lobophylliidae Lobophylliid corals 4
These stony corals have big, fleshy, colorful polyps over a hard skeleton. Acan and Lobo corals belong here.
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Genus Homophyllia 1
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Genus Lobophyllia carpet brain coral 2
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Genus Micromussa Micromussa corals 1
Micromussa corals have big, soft, brightly colored polyps on a hard skeleton. The acan lord coral is one of them.
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Family Pocilloporidae Pocilloporid corals 1
These stony corals usually grow as branching bushes with small polyps. Birdsnest and cauliflower corals belong here.
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Genus Seriatopora birdsnest corals 1
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Order Zoantharia Zoanthids 1
Zoanthids are small polyps that live in mats or colonies and have no hard skeleton. They look a bit like tiny sea anemones joined together.
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Family Zoanthidae Button polyps 1
This family of zoanthids has smooth polyps joined at the base, like a carpet of colorful buttons. Unlike some cousins, they do not stick sand into their skin. Part of Brachycnemina
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Genus Zoanthus button polyps 1
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Class Octocorallia Octocorals 3
Each octocoral polyp has exactly eight feathery tentacles. Soft corals, sea fans and sea pens belong here.
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Order Malacalcyonacea Soft corals and sea fans 2
This order holds most soft corals, such as leather corals and Kenya trees, plus many sea fans. Scientists named it in 2022 after studying octocoral DNA.
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Family Capnellidae Kenya tree corals and kin 1
This family of soft corals was named in 2022. It joins tree-shaped Kenya tree corals with some soft corals from cold northern seas.
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Genus Capnella Kenya tree corals 1
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Family Sarcophytidae Leather corals 1
These soft corals feel tough and rubbery, like leather. They include toadstool and devil's hand leathers, and many make strong chemicals.
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Genus Sarcophyton toadstool leather corals 1
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Order Scleralcyonacea Sea pens, blue corals and kin 1
This order of octocorals includes sea pens, blue coral, red precious coral and star polyps. It was named in 2022, when scientists studied octocoral DNA.
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Family Briareidae Briareid soft corals 1
This family of octocorals forms rubbery mats or fingers on rock. Its polyps can pull back into the mat when they are touched.
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Genus Briareum Star polyps 1
Star polyps form a purple or brown mat covered in little star-shaped polyps. Green star polyps are a common aquarium coral.
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Phylum Echinodermata Echinoderms 7
Echinoderms are sea animals whose bodies are usually built in five matching parts. They move on hundreds of tiny tube feet, and many have spiny skin.
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Subphylum Asterozoa Sea stars and brittle stars 3
These echinoderms have star-shaped bodies with arms spreading out from the middle. The group includes sea stars and brittle stars.
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Class Asteroidea Sea stars 3
Sea stars, or starfish, usually have five arms joined to a central disc. Most can grow back an arm they lose.
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Infraclass Neoasteroidea 3
Part of Ambuloasteroidea
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Order Spinulosida 1
Part of Spinulosacea
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Family Echinasteridae 1
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Genus Echinaster 1
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Superorder Valvatacea Biscuit stars, sand stars and kin 2
This big group of sea stars includes cushion stars, biscuit stars and sand-burrowing stars. Many have rows of large plates around the edge of their arms.
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Order Paxillosida Burrowing sea stars 1
These sea stars live on sand and mud and often dig in. Their tube feet are pointed instead of having suckers.
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Family Astropectinidae Comb stars 1
Comb stars are flat sea stars with stiff spines along the edges of their arms, like a comb. They bury in sand and swallow small animals whole.
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Genus Astropecten Sand stars 1
Sand stars are fast sea stars that bury themselves in sand. They swallow snails, clams and other small animals whole.
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Order Valvatida Cushion and biscuit stars 1
This order of sea stars includes cushion stars, biscuit stars and blue Linckia stars. Many have stiff bodies covered in neat plates.
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Family Goniasteridae Biscuit stars 1
Biscuit stars have stiff, flat bodies edged with big, neat plates, a bit like a cookie. Many are brightly colored.
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Genus Fromia Fromia sea stars 1
Fromia are small, colorful sea stars from the Indian and Pacific Oceans. They graze on thin films on rocks.
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Subphylum Echinozoa Sea urchins and sea cucumbers 4
These echinoderms have no arms. Their bodies are shaped like a ball or a sausage, as in sea urchins and sea cucumbers.
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Class Echinoidea Sea urchins 3
Sea urchins have a round shell covered in spines. They chew food with five teeth set in a jaw called Aristotle's lantern.
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Order Camarodonta Common sea urchins 3
This order holds many of the round, spiny sea urchins people see most often, from rocky shores to reefs. Part of Euechinoidea › Carinacea › Echinacea
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Superfamily Odontophora 2
Part of Echinidea
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Family Echinometridae 1
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Genus Echinometra 1
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Family Toxopneustidae 1
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Genus Lytechinus 1
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Family Temnopleuridae Temnopleurid urchins 1
These sea urchins are usually small and have little pits or grooves on their shells. The tuxedo urchin belongs here. Part of Temnopleuridea
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Genus Mespilia Tuxedo urchins 1
These small sea urchins have bands of short spines with bare, colorful stripes between them. They often carry bits of shell or algae on their backs.
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Class Holothuroidea sea cucumbers 1
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Order Holothuriida 1
Part of Actinopoda
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Family Holothuriidae 1
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Genus Holothuria 1
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Phylum Mollusca Molluscs 9
Molluscs are soft-bodied animals, and many of them grow a hard shell. Snails, clams and octopuses are all molluscs.
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Class Gastropoda Snails and slugs 9
Gastropods crawl on one big, slimy foot. Most carry a single coiled shell, but sea slugs have lost theirs.
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Subclass Caenogastropoda 4
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Order Caenogastropoda (unplaced) 1
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Family Cerithiidae cerithids (ceriths) 1
Part of Cerithioidea
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Order Littorinimorpha Periwinkles, conchs, cowries and kin 1
This is a huge group of sea snails. It includes periwinkles, cowries and the jumping conchs.
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Family Strombidae True conchs 1
True conchs have eyes on long stalks. They move by jumping with a hooked foot, and most of them eat algae. Part of Stromboidea
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Genus Gibberulus humped conchs 1
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Order Neogastropoda Whelks, cone snails and kin 2
These sea snails have a long tube, or siphon, that they use to smell the water. Many hunt other animals or eat dead ones.
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Superfamily Buccinoidea whelks 2
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Family Fasciolariidae spindle shells and tulip shells 1
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Family Nassariidae Nassa snails 1
Nassa snails are small sea snails that live in sand and mud. They sniff out dead animals with a long breathing tube and rush in to eat them.
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Genus Phrontis American nassa snails 1
Phrontis is a group of small nassa snails from the Americas. They live in sand and quickly find leftover food. Part of Nassariinae
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Order Cycloneritida 1
Part of Neritimorpha
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Family Neritidae nerites 1
Part of Neritoidea
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Order Trochida Top and turban snails 4
These sea snails have shells shaped like a spinning top or a turban. Many graze on algae on rocks. Part of Vetigastropoda
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Superfamily Trochoidea 4
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Family Trochidae top shells 1
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Family Turbinidae Turban snails 3
Turban snails have thick, rounded shells. They close the opening with a hard, round lid when they hide.
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Subfamily Turbininae 3
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Genus Lithopoma star snails (astrea snails) 1
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Genus Turbo Turbo snails 2
Turbo snails are turban snails with heavy shells and a thick, round lid. They scrape algae off rocks.
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