Crustaceans. Invertabrates. Molusks. Echinoderms

Common Name
Scientific Name
Anemone Shrimp Periclimenes yucatanicusAnemone Shrimp, Periclimenes Yucatanicus and Bubble Tip Anemone, Entacmaea quadricolor, in Grand Cayman (Steven Smeltzer) Most often seen residing in Condylactys gigantae in the Caribbean. However, it has other host anemones: B. annulata, A. pallida, and Lebrunia dannae. (Williams & Williams, 1981, Spotte, 1997) These shrimp wait outside their host and advertise their presence by waving their antennae or swimming up and down in the water column. This serves to bring animals to their location, so that the shrimp can remove and ingest dead skin cells, fungus, and parasites. Often a ‘cleaning station’ is rather apparent, with several, often large fish waiting their turn to be cleaned.
Arrow Crab Stenorhynchus seticornisArrow Crab, Stenorhynchus seticornis, night dive on the Oro Verde Wreck, Grand Cayman (Steven Smeltzer) Stenorhynchus seticornis is found in the western Atlantic Ocean, from North Carolina and Bermuda to Brazil, including throughout the Caribbean Sea. It lives on coral reefs at depths of 10–30 feet (3.0–9.1 m). The body of S. seticornis is triangular, and the rostrum is drawn out into a long point with serrate edges. The legs are also long and thin,, up to 10 cm (3.9 in) across, and the animal’s carapace may be up to 6 centimeters (2.4 in) long. Coloration is variable in this species: the body may be golden, yellow or cream, marked with brown, black or iridescent blue lines; the legs are reddish or yellow, and the claws are blue or violet. The Arrow Crab, also known as the Spider Crab, has extremely long legs. It is called the Arrow Crab because of the shape of the body and head. The size is variable, many reaching six inches, and some up to 10 inches. Females may be dramatically smaller. Different species inhabit different parts of the world. The most common Arrow Crab (Stenorhynchus seticornis) comes from the Caribbean, but other species are imported from the Indo-Pacific region, eastern Africa, and California. They normally inhabit portions of the reef usually associated with a small cave or crevice. S. seticornis is nocturnal and territorial. It eats small feather duster worms and other coral reef invertebrates.
Banded Spiny Lobster Panulirus marginatusBanded Spiny Lobster Maui Hawaii (Steven Smeltzer) Only known from the Hawaiian Islands, including Pearl and Hermes Reef, and Laysan Island. Antennular plate with two large widely separated spines, with scattered small spinules behind these. Exopod of third maxilliped present, with flagellum. Upper surface abdomen pubescent in grooves only. Transverse groove of abdominal somites with straight margins, not crenulated. Transverse grooves of abdominal somites 2 to 4 join the groove along the anterior margin of the corresponding pleuron. Anterior margin of pleuron abdominal somite two with distinct teeth.
Colour: carapace with yellowish, reddish and brownish colour, not spotted. Abdomen bright to dark purple with a conspicuous transverse yellow band over the middle of each somite. Legs rather uniform in colour, with a few spots, but not streaked. Antennulae rather uniform in colour.
Black-lipped Pearl Oyster Pinctada margaritiferaBlack-Lipped Pearl Oyster, Pinctada margaritifera, Corals reef, scuba dive, scuba diving, reefs, Fish pictures, Pictures of fish, coral reefs, Maui Hawaii (Steven Smeltzer) The Black-lip pearl oyster is a marine bivalve mollusk native to the Indo-Pacific. Their natural habitat are the lagoons and shallow coastal areas In the adult phase, they attach themselves by byssal threads to their rocky habitat and can be found from 1 to 40 meters in depth (Wada 1991). These adults are broadcast spawners, and as such, the females release millions of eggs into the water column to mix randomly with the sperm of males. Upon external fertilization, the eggs develop into free-swimming larvae. After approximately a month, these larvae attach themselves to the substrate and metamorphose into small juvenile oysters (known as “spat”). Each oyster begins its life as a male. After a few years, they undergo another transformation which leaves them sexually female (Ellis and Haws 1999). The lifespan of these organisms can be as long as 60 years.
Brown Slipper Lobster Parribacus antarcticusBrown Slipper Lobster, Parribacus antarcticus, Maui Hawaii (Steven Smeltzer) Found in Hawaiian, Indo-Pacific, Caribbean and tropical Atlantic waters. Slipper lobsters are a family of achelate (clawless) decapod crustaceans found in all warm oceans and seas. Despite their name, they are not true lobsters, but are more closely related to spiny lobster
Candy Cane Shrimp Parhippolyte misticaCandy Cane Shrimp Maui Hawaii.  Sheraton reef. (Steven Smeltzer) Indo-Pacific, including Hawai’i These brightly-striped shrimp are rare in Hawai’i. They have typically only been found deep within coastal submarine tunnels (underwater lava tubes) more than 20 feet from the surface. Because of their unusual habitat, they are rarely seen and little is know about their biology and ecology in Hawai’i.
The same shrimp has been reported in coastal regions of relatively small rocky islands through the Pacific and Indian Oceans, from Hawai’i nearly to Africa. While they appear to be restricted to underwater tunnels in Hawaii, elsewhere these shrimp are found in shallower, more accessible habitats, including intertidal pools, rock fissures, and open caves that are flooded by the ocean or underground seawater.
Caribbean Spiny Lobster Panulirus argusSpiny Lobster, Palinuridae argus, hiding under ledge Grand Cayman (Steven Smeltzer) Found in tropical and subtropical waters of the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico Caribbean spiny lobsters, Panulirus argus (Latreille, 1804), aka Florida spiny lobsters, grow to about 60 external link cm in length. Like the other 20 members of the genus Panulirus external link such as the Australian, California, and Chinese spiny lobsters, they lack the large pinching claws of their Maine lobster relatives. Their primary defense are the spines that cover its shell, which help protect the lobster from predators. Caribbean spiny lobsters use a second pair of antennae in sensory perception, which are found folded along side the body when not in use. These lobsters have a striped body, brown-gray in color with yellow spots on the segmented tail. They have compound eyes and can detect orientation, form, light, and color. If startled, lobsters will kick their large abdominal tails rapidly to swim away backwards to safety.
Crown of Thorns Acanthaster planciCrown of Thorns starfish, Acanthaster planci, (Linnaeus, 1758), Lanai Hawaii (Steven Smeltzer) It is endemic to tropical coral reefs in the Red Sea, the Indian Ocean, and the Pacific Ocean. The crown-of-thorns starfish (Acanthaster planci) is a large nocturnal sea star that preys upon coral polyps. The crown-of-thorns receives its name from venomous thorn-like spines that cover its body. As solitary animals, they feed alone and maintain constant distance between themselves and other members of their species.  The sharp spines on the sides of the starfish’s limbs resemble thorns and create a crown-like shape, giving the creature its name. The thorns are very sharp and are capable of piercing through standard wetsuits and other clothing.[citation needed] They are also venomous. When the crown-of-thorns feed, they release a chemical which is known to attract more starfish to the area.
Cushion Star Culcita novaeguineaeCushion Starfish, Culcita novaeguineae, off coast of Kihei, Maui Hawaii (Steven Smeltzer) Found in the Adaman Sea and tropical waters of western Pacific The cushion star looks more like a spineless sea urchin than a starfish.  This large and very common sea star   has a pentagonal shape with very short arms. Its color is extremely variable: beige, brown, red, yellow, green, with plates and tubercles often in contrasting color compared with the background. 30 cm diameter.
It is very common in lagoon, back reef and reef front. It feeds on detritus and on sessile invertebrates, sometimes including hard corals (anyway it can not be considered a serious threat for the coral reefs).
Flamingo Tongue Cyphoma gibbosumFlamingo Tongue, Cyphoma Gibbosum, on Grogornian fan Grand Cayman (Steven Smeltzer)Flamingo Tongue, Cyphoma Gibbosum, Grand Cayman (Steven W Smeltzer)




It is the most common of several species in the genus which live in the tropical waters of the Western Atlantic Ocean, including the Caribbean Sea, the Gulf of Mexico and the Lesser Antilles. It can also be found from North Carolina, the Bermudas to Northern Brazil. the snail appears bright orange-yellow in color with black markings. However, these colors are not in the shell, but are only due to the thin flaps of live mantle tissue which usually cover the shell. The mantle flaps can be retracted, exposing the shell, but this usually happens only when the animal is attacked.  The flamingo tongue feeds by browsing on the living tissues of the soft corals on which it lives. Common prey include Briareum spp., Gorgonia spp., Plexaura spp., and Plexaurella spp. Adult female C. gibbosum attach eggs to coral which they have recently fed upon. After roughly a week and a half, the larvae hatch. They are planktonic and eventually settle onto other gorgonian corals. Juveniles tend to remain on the underside of coral branches while adults are far more visible and mobile. Adults scrape the polyps off the coral with their radula, leaving an easily visible feeding scar on the coral. However, the corals can regrow the polyps, and therefore predation by C. gibbosum is generally not lethal.
Red Swimming Crab Gonioinfradens paucidentataRed Swimming Crab, Gonioinfradens paucidentata, Night dive, Sheraton Reef, Maui Hawaii (Steven Smeltzer) Found in Indio Pacific region There are almost 200 species of crabs in Hawaii. The scientific name of crabs is decapod crustaceans, a name that applies to true crabs, which typically have a very short projecting tail or a short abdomen that’s hidden under the thoraxCrabs are omnivores and primarily eat algae, but also other foods that they find, including bacteria, fungi, worms and other crustaceans.
Rough Spined Sea Urchin Prionocidaris hawaiiensisRough Spined Sea Urchin, Prionocidaris hawaiiensis, near Kihei on the island of Maui, Hawaii (Steven Smeltzer) This species is known only from Hawai’i and New Caledonia Sea Urchins have radially symmetrical bodies divided into 5 equal parts.  They move about using articulating spines and tube feet.  Jawed tube feet called pedicellariae are employed for defense along with sometimes venomous spines.  Urchins feed upon algae, sponge, or detritus.  Their hard jaws and stout spines are capable of eroding coral or rock in some species.The rough-spined urchin belongs to the Family Cidaridae, a primitive group of urchins with large, blunt primary spines, ringed at their bases by smaller secondary spines. The spines of these urchins lack the living skin tissue present in other urchin species, and the primary spines usually become covered with a layer of algae, surface-dwelling invertebrates, and detritus.
Sea Star Valvaster striatusSea Star, Valvaster stiatus, Maui Hawaii (Steven Smeltzer) Found widely throughout the Indo-Pacific including Guam, the Philippines, Australia, and the Indian Ocean. in less than 20 m depth. Its definitely a RARELY encountered, but thankfully, easy to identify, species in Hawaii (known from Oahu and Maui),   We DO know something about the etymology of its name, of course. Notice that on the side of the animal, are large bivalved pedicellariae, which are sort of like big clamps that sit on the lateral side of the animal (see white circles below). Hence Valv for the valves on each pedicellariae and -aster for star.. And the adjective striatus refers to the striated patterns on the body surface
Slate Pencil Urchin Heterocentrotus mammillatusSlate Pencil Urchin, Heterocentrotus mammillatus,  on Maui, Hawaii near Kihei (Steven Smeltzer)  Indo-Pacific, Hawaii The Slate Pencil Urchin, also known as Red Slate Pencil Urchin, has a reddish-tan body with sparse, long, blunt solid spines that taper at the tips and radiate out from the body in all directions at lengths of up to five inches. In addition to its spines looking like pencils, this sea urchin is also called the Slate Pencil Urchin because its spines were used as writing utensils for slate boards.  In old Hawaii, it was known as ha’uke’uke ‘ula’ula, and its eye-catching red spines sometimes were carved decoratively, used as marking tools and possibly even for early cosmetic coloring.
Sleepy Sponge Crab Dromia dormiaSleepy Sponge Crab, Dromia dormia, off west coast of Maui, Hawaii (Steven Smeltzer)Sleepy Sponge Crab Close up, Dromia dormia, off west coast of Maui, Hawaii (Steven Smeltzer)  Dromia dormia has a widespread distribution in the Indo-Pacific region. Its range extends from East Africa (including Madagascar, the Seychelles and Mauritius) and the Red Sea through the Malay Archipelago, south to Queensland (Australia), north to China and Japan and as far east as Hawaii and French Polynesia.[1][2] It is mostly found in shallow waters, with the deepest record being 112 m (367 ft)  Like other related crabs, D. dormia camouflages itself by carrying a sponge on its back, which it cuts to size with its claws, and then holds in place with its last two pairs of legs.[5] Instead of a sponge, D. dormia has occasionally been observed carrying other materials, including a hollow piece of wood, and the sole of a discarded shoe.[2]
Spiny Sea Urchin EchinozoaSpiny Sea Urchin, west coast of Maui, Hawaii (Steven Smeltzer) Found in all oceans. Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. Their shell, or “test”, is round and spiny, typically from 3 to 10 centimetres (1.2 to 3.9 in) across. Common colors include black and dull shades of green, olive, brown, purple, and red. They move slowly, feeding mostly on algae. Sea otters, wolf eels, triggerfish, and other predators feed on them. Humans harvest them and serve their roe as a delicacy.  Sea urchins are members of the phylum Echinodermata, which also includes sea stars, sea cucumbers, brittle stars, and crinoids. Like other echinoderms they have fivefold symmetry (called pentamerism) and move by means of hundreds of tiny, transparent, adhesive “tube feet”. The symmetry is not obvious in the living animal, but is easily visible in the dried test. “Echinodermate” means “spiny skin” in Greek.  Specifically, the term “sea urchin” refers to the “regular echinoids,” which are symmetrical and globular. The term includes several different taxonomic groups: the order Echinoida, the order Cidaroida or “slate-pencil urchins”, which have very thick, blunt spines, and others. Besides sea urchins, the class Echinoidea also includes three groups of “irregular” echinoids: flattened sand dollars, sea biscuits, and heart urchins.
Together with sea cucumbers (Holothuroidea), they make up the subphylum Echinozoa, which is characterized by a globoid shape without arms or projecting rays. Sea cucumbers and the irregular echinoids have secondarily evolved diverse shapes. Although many sea cucumbers have branched tentacles surrounding the oral opening, these have originated from modified tube feet and are not homologous to the arms of the crinoids, sea stars, and brittle stars.
Sponge Brittle Star OphiuridaBrittle Star on Pink Vase Sponge, Niphates digitalis, Grand Cayman (Steven Smeltzer)

Sponge Brittle Star, Ophiothrix suensoni, Lütken, 1856, Grand Cayman (

Ophiuroids can be found today in all of the major marine provinces, from the poles to the tropics. Brittle stars, or ophiuroids, are echinoderms, closely related to starfish. They crawl across the seafloor using their flexible arms for locomotion. The ophiuroids generally have five long slender, whip-like arms which may reach up to 60 centimetres (24 in) in length on the largest specimens. They are also known as serpent stars.
Ophiuroidea contains two large clades, Ophiurida (brittle stars) and Euryalida (basket stars). Many of the ophiuroids are rarely encountered in the relatively shallow depths normally visited by humans, but they are a diverse group.
There are some 1,500 species of brittle stars living today, and they are largely found in deep waters more than 500 metres (1,650 feet) down.  Ophiuroids can be found today in all of the major marine provinces, from the poles to the tropics. In fact, crinoids, holothurians, and ophiuroids live at depths from 16–35 m, all over the world. Basket stars are usually confined to the deeper parts of this range. Ophiuroids are known even from abyssal (>6000 m) depths. However brittle stars are also common, if cryptic, members of reef communities, where they hide under rocks and even within other living organisms. A few ophiuroid species can even tolerate brackish water, an ability otherwise almost unknown among echinoderms. A brittle star’s skeleton is made up of embedded ossicles.