An echinoderm is any member of the phylum Echinodermata of marine animals. The adults are recognizable by their radial symmetry, and include starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest phylum that has no freshwater or terrestrial members.
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as Asteroids due to being in the class Asteroidea. About 1,500 species of starfish occur on the seabed in all the world's oceans, from the tropics to frigid polar waters. They are found from the intertidal zone down to abyssal depths, 6,000 m (20,000 ft) below the surface.
The crown-of-thorns starfish, Acanthaster planci, is a large starfish that preys upon hard, or stony, coral polyps (Scleractinia). The crown-of-thorns starfish receives its name from venomous thorn-like spines that cover its upper surface, resembling the biblical crown of thorns. It is one of the largest starfish in the world.
External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. It is contrasted with internal fertilization, in which sperm are introduced via insemination and then combine with an egg inside the body of a female organism. External fertilization typically occurs in water or a moist area to facilitate the movement of sperm to the egg. The release of eggs and sperm into the water is known as spawning. In motile species, spawning females often travel to a suitable location to release their eggs. However, sessile species are less able to move to spawning locations and must release gametes locally. Among vertebrates, external fertilization is most common in amphibians and fish. Invertebrates utilizing external fertilization are mostly benthic, sessile, or both, including animals such as coral, sea anemones, and tube-dwelling polychaetes. Benthic marine plants also use external fertilization to reproduce. Environmental factors and timing are key challenges to the success of external fertilization. While in the water, the male and female must both release gametes at similar times in order to fertilize the egg. Gametes spawned into the water may also be washed away, eaten, or damaged by external factors.
Charonia tritonis, common name the Triton's trumpet or the giant triton, is a species of very large sea snail, a marine gastropod mollusc in the family Charoniidae, the tritons. Reaching up to two feet in shell length this is one of the biggest mollusks in the coral reef.
Acanthaster is a bitypic genus of large and venomous starfish placed in its own family, Acanthasteridae. Its two members are known as crown-of-thorns starfish. Acanthaster are native to Coral reefs in Indo-Pacific region. They are a contributor to coral reefs degradation because at high density they consume a large amount of live coral.
Pisaster brevispinus, commonly called the pink sea star, giant pink sea star, or short-spined sea star, is a species of sea star in the northeast Pacific Ocean. It was first described to science by William Stimson in 1857. The type specimen was collected on a sandy bottom, 10 fathoms (18 m) deep, near the mouth of San Francisco Bay.
Corynactis is a genus of colonial anthozoans similar in appearance to sea anemones and in body format to scleractinian stony corals. These animals are cnidarians in the family Corallimorphidae. Large unidentified polyps of this genus feed on the crown-of-thorns seastar Acanthaster planci and may help control the crown-of-thorns population.
The purple sunstar, northern sunstar, or smooth sun star, Solaster endeca, is a species of starfish in the family Solasteridae.
Pteraster tesselatus, the slime star or cushion star, is a species of starfish in the family Pterasteridae found in the North Pacific.
Pocillopora verrucosa, commonly known as cauliflower coral, rasp coral, or knob-horned coral, is a species of stony coral in the family Pocilloporidae. It is native to tropical and subtropical parts of the Indian and Pacific Oceans.
Anomastraea is a monotypic genus of corals in the family Coscinaraeidae. It is represented by a single species, the crisp pillow coral.
Acropora acuminata is a species of acroporid coral found in Australia, the Red Sea, the central Indo-Pacific, Japan, the northern Indian Ocean, the East China Sea, southeast Asia, and the western Pacific Ocean. It is particularly susceptible to coral bleaching, the crown-of-thorns sea star, and harvesting for the aquarium trade. It is found on shallow coral reefs from depths of 5–20 m. It was described by Verrill in 1864.
Acropora hyacinthus is a species of acroporid coral found from the Indian Ocean, the Indo-Pacific waters, southeast Asia, Japan, the East China Sea and the western Pacific Ocean. It lives on shallow reefs on upper reef slopes, and is found from depths of 1–25 m. Crown-of-thorns starfish preferentially prey upon Acropora corals. It was described by Nemenzo in 1971.
Acropora gemmifera is a species of acroporid coral found in the Gulf of Aden, the Red Sea, the central Indo-Pacific, the southwest and northern Indian Ocean, southeastern Asia, Australia, the East China Sea, Japan, the oceanic central and western Pacific Ocean, and northwestern Hawaiʻi. It occurs on exposed upper reef flats and slopes, from depths of 1–15 m. It was described by Brook in 1892.
Acropora globiceps is a species of acroporid coral found in the oceanic central and western Pacific Ocean and central Indo-Pacific. It can also be found in the Great Barrier Reef, the Philippines, the Andaman Islands, Polynesia, Micronesia and the Pitcairn Islands. It occurs on the slopes of reefs, the flats of reefs, in tropical shallow reefs, and at depths of around 8 metres (26 ft). It was described by Dana in 1846.
Acropora palmerae is a species of acroporid coral found in the northern Indian Ocean, the central Indo-Pacific, Australia, Southeast Asia, Japan, the East China Sea and the oceanic west Pacific Ocean. It is also found in Palau and the Mariana Islands, American Samoa, the Andaman Islands, the Great Barrier Reef, Okinawa Island, Mauritius, Micronesia, the Cook Islands and the Philippines. It occurs in tropical shallow reefs on flats exposed the action of strong waves and in lagoons, from depths of 0 to 12 metres. It was described by Wells in 1954.
Acropora tenuis is a species of acroporid coral found in the Red Sea, the Gulf of Aden, the southwest, northwest and northern Indian Ocean, the Persian Gulf, the central Indo-Pacific, Australia, Southeast Asia, Japan, the East China Sea and the oceanic west and central Pacific Ocean. It occurs in tropical shallow reefs on upper slopes and in subtidal habitats, at depths of 8 to 20 metres.
Paracorynactis is a genus of corallimorphs from the western Indo-West Pacific. They are specialized predators of echinoderms, and are notable for preying on the destructive crown-of-thorns starfish among others. The genus is monotypic with the single species, Paracorynactis hoplites.
Turbinaria is a genus of colonial stony corals in the family Dendrophylliidae. Common names for this genus include disc coral, scroll coral, cup coral, vase coral, pagoda coral and ruffled ridge coral. These corals are native to the Red Sea, Indian Ocean, Japan and the south Central Pacific Ocean.
