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A Fishwatcher's Guide to the Marine Invertebrates of Hawai'i

Part 2 of 4, To: Part 1, Part 3Part 4,

Bob Fenner

Porites compressa

Stinging Celled Animals, Phylum Cnidaria

Hydroids and Siphonophores:

Gymnangium hians (Busk 1852), Feather Hydroid. Found in areas of good current on underhangs, in caves (pukas). Gray to light brown in color. 2-3 inches in length. Indo-Pacific. Hawaii pix.

Pennaria disticha Goldfuss 1820. Cosmopolitan in tropical, temperate seas. To 12 cm. in height. Urn-shaped polyps are born on upper sides of immediately alternating branches. N. Sulawesi and Nuka Hiva, Marquesas images. 

Zoanthids: Colonial Anemones

Palythoa caesia Dana 1848. Rubbery appearing common mat, flattened polyps exposed to varying degrees to 3 cm. diameters. Tentacle ends look like knobs. Dark brown to tan in color. Western Pacific. Hawai'i pix. 

Soft Corals:

Anthelia edmondsonii (Verrill 1928). Light blue in color this is one of the few soft corals found in Hawai'i (and only there). Predated nightly by the nudibranch Tritonia hawaiiensis. 1/4" inch across polyps in colonies 3-12" across.  Big Island photos. 

Sinularia abrupta Tixier-Durivault 1970, Leather Coral. Western and Central Pacific. Easy to miss in the wild. Short (two inch maximum height), flexible lobes on a flat base. Image shot at Shark Point, O'ahu, Hawai'i.

Stony Corals: 

    Where's the group spiel Bob? Oh, saving it for the tome "Hawai'i Underwater" guide I see...

Family Acroporidae:

Montipora capitata (Dana 1846), Rice Coral. Encrusting to massive colonies to thin plates in calm water. Dark to light brown  in color. Hawaiian endemic. Structural elements of polyps appear like grains of rice. 

Montipora flabellata Studer 1901, Most colonies are fluorescent blue to purplish in color, though they can be brown. Shallow water (to 20 feet). Hawaiian endemic. 

Family Agariciidae: Elephant Skin Corals. Ridges of corallites (the septo-costae) interconnect adjacent calyces. Have very short tentacles and therefore are thought to feed more by mucus entrapment of suspended material than by stinging collection. Genus Leptoseris: Six Hawaiian species (three deepwater). Septa are long, fine and generally curved. Genus Pavona (three local species), septa are shorter and straight.  

Leptoseris incrustans (Quelch 1886), Swelling Coral. Most common member of the genus in Hawai'i. Identified by swellings of septo-costae between the calyces. Colonies of only a few inches across occur under ledges, generally in deeper water. Tan to reddish-brown to greenish in color. Indo-Pacific. Kona, HI pic. 

Leptoseris hawaiiensis Vaughan 1907. Colonies as encrusting laminae. Corallites raised irregularly, rounded. Septae costae even. Green or brown in color. East Africa, Red Sea to Hawai'i, Tuamotus and tropical East Pacific. Nuka Hiva, Marquesas, Polynesia pic. 

Pavona duerdeni Vaughan 1907. Massive colonies (up to 10 feet tall) of irregular appearance (sometimes huge).  Red Sea and Hawai'i images. Found in areas of moderate current, wave movement Named in honor of cnidarian scientist J. E. Duerden (1865-1937).

Pavona varians Verrill 1864. Colonies encrusting to laminar, showing short, irregular valleys.  Hawai'i images.

Family Pocilloporidae: Cat's Paw Corals. Have bumpy appearance due to raised verrucae. 

Pocillopora damicornis (Linnaeus 1758), Cauliflower Coral. The most common member of the family offered to the aquarium trade. Compact clumps of up to a few meters height. Verrucae and branches blend together. Of varying branch thickness (thinner in greater depths, less water motion areas). Several colors: overall brown, pink cream, greenish. Colony and close-up of Pulau Redang specimens and close-up of the species off Cabo Pulmo, Mexico's Sea of Cortez in the tropical eastern Pacific below.
Pocillopora eydouxi Milne Edwards & Haime 1860, Brush Coral. Distinctive large, upright branches with light-colored ends. A common species over its wide range.  Shown in Hawai'i.

Pocillopora meandrina Dana 1846. Flat, short, curved branches, small verrucae. Regular arrangement of branch growth, verrucae placement. At right: Bunaken/Sulawesi/Indo. and Hawai'i close-ups,  and two images of this common species in Hawai'i below.

Family Poritidae:

Porites compressa Dana 1846, Finger Coral. Another common (endemic) species in Hawai'i (85% or so of Kaneohe Bay, O'ahu). Generally light brown in color.  Finger like deeper, to knobby boulders in shallow. Below, shallow to deeper pics.
Porites evermanni Vaughan 1907, Evermann's Coral. A massive form that is sometimes similar to P. lobata (below), but never yellow in color (brown to gray to purple). Commonly knobby and fuzzy at close inspection (the latter due to partly retracted polyps). Likely endemic to Hawai'i. Image with P. lobata in background.

Porites lobata Dana 1846, Lobe Coral. The most common coral species in Hawai'i. Found as encrusting colonies in high wave action areas to fifteen foot high mounds in protected areas. Yellow to greenish in color. Often with grooves caused by the Snapping Shrimp Alpheus deuteropus. Below: close up of an encrusting colony, one showing shrimp space parasite marking (both Hawai'i) and a huge colony (grow about an inch tall per year) in the Maldives. At right, Hawaiian specimen with pink worm parasites (Trematode, flatworm) that Butterflyfishes pick at, consume, continuing the life cycle.

Porites rus Forsskal 1775, Plate and Pillar Coral. Variable in shape as its common name points to. Upright columns more shallow to gorgeous plates deeper, more calm waters. Gray to brown in color, often with yellow polyps that have wider spaced calyces, raised areas between polyps. Both morphs visible here at Honaunau, City of refuge, Kailua, Kona, Hawai'i.

Family Fungiidae: Plate Corals: Seven species, three genera recorded from Hawai'i

Cycloseris vaughani  Boschma 1923, Vaughan's Razor Coral. Circular in shape, flat on the bottom. Found on hard surfaces in shallow depths (to forty feet or so). Six prominent septal ribs. Big Island pic.

Fungia concinna Verrill 1864, Disk Coral. Flat, circular skeletons to six inches in diameter. Septal teeth small. Very small tentacular lobes or none. Underside lacks pits. Here off Hawai'i's Big Island at night. 

Fungia scutaria Lamarck 1801. Oval, heavy polyps with high, regularly placed tentacular lobes. To seven inches. Indo-Pacific. Occur in many colors. Largest, most common fungiid in Hawai'i. 

Family Agariciidae: 

Leptoseris hawaiiensis Vaughan 1907. Colonies as encrusting laminae. Corallites raised irregularly, rounded. Septae costae even. Green or brown in color. East Africa, Red Sea to Hawai'i, Tuamotus and tropical East Pacific. Nuka Hiva, Marquesas, Polynesia pic. 

Pavona duerdeni Vaughan 1907. Massive colonies of irregular appearance (sometimes huge).  Red Sea image.

Pavona varians Verrill 1864. Colonies encrusting to laminar, showing short, irregular valleys.  Hawai'i images.

Family Faviidae: Honeycomb Corals

Leptastrea purpurea (Dana 1846). Crust Coral. Encrusting to lobe-like. Large (1/8") calyces with walls touching. Indo-Pacific. Here in Hawai'i. 

Family Dendrophylliidae:

Balanophyllia sp. Either B. hawaiiensis or B. cf. affinis. Here off Hawai'i's Big Island at night, though can be found in caves and crevices open during daylight hours. About one inch in all dimensions. 

Tubastrea coccinea Lesson 1831, Orange Cup Coral. Caribbean and Indo-Pacific. Right: Closed, open colony pix in the Bahamas. Below, close up of a colony under an arch off of Kailua Kona and exhibit images shot at the Waikiki Aquarium.

Order Antipatharia: Black Corals, Whip Corals

Cirripathes anguina Dana 1846, Common Whip Coral. Often twisted on its singular axis. Polyps arrayed on two opposing sides of skeleton. Hawaiian Whip Corals are commensal hosts to two species of gobies (which often denude the anterior tip to lay their eggs) and two species of pontonid shrimp. Found in forty plus foot depths, sticking out into currents. Up to three feet in length. Kona pix. 



Pseudoceros dimidiatus von Graff 1893. Look for the double yellow "racing stripe" down the middle for this species. Other markings are variable to missing.  Central to western Pacific. This one off of Kailua Kona, Hawai'i. 

Pseudoceros ferrugineus Hyman 1959. The Fuchsia Flatworm Central and Western Pacific at moderate depths. Out during both day and night, often appearing bluish until artificial light is applied, and more round when fully opened. Hawaii pix. 

Polychaete Worms:

Sabellastarte sanctijosephi (Gravier 1908). Indo-Pacific; Eastern Africa to the Cook Islands. Image shot off of Hawai'i, Malaysia. Characterized by their two tentacular crown head. 

Spirobranchus giganteus Pallas 1766, Horned Christmas Tree, aka Bisma Rock Worms. Cosmopolitan; all tropical seas. Most often found in association (burrowed in) Porites and Millepora. To an inch in diameter. Hard to maintain in captivity over any period of time. Need frequent particulate feedings, low light. Pulau Redang, Malaysia photo.

Loimia medusa (Savigny 1820), the Medusa or Spaghetti Worm. Cosmopolitan; all tropical seas. Found between rocks in silt to sandy substrates. Tube-dwelling (family Terebellidae) worm that is most often recognized by its extended feeding tentacles. Hawai'i image. 


Crisina radians (Lamarck 1816), the Tuning Fork Bryozoan. A calcareous species found on hard surfaces and seaweed blades. Ends of colonies look like tuning forks. To about a half inch across. Kona, Hawai'i. images.

Triphyllozoon sp. perhaps T. inornatum Harmer 1934. Found on walls in areas of high current. Hydroid polyps with capitate tentacles. Western Pacific; New Guinea, Indonesia, Philippines. N. Sulawesi and Hawai'i images.



Nerites & Periwinkles: Families Neritidae and Littorinidae

Nerita picea (Recluz 1841), the Black Nerite (Pipipi in Hawaiian). A Hawaiian endemic. To about a half inch in length. Found in the splash zone to high and dry above there (but below Periwinkles), more actively grazing at night. Shiny black globose shells with fine gray spiral lines. 

Family Hipponicidae: Hoof Shells. Attach limpet-like to the substrate and don't move. Unlike true limpets (family Patellidae) these snails show spiral growth in their shells. Four Hawaiian species. 

Hipponix imbricatus Gould 1846. Shingly Hoof Shell. At times very abundant on the outsides of smooth boulders. Shallows to about fifty feet of depth. May be endemic to Hawai'i. To about half an inch in diameter. 

Families Ranellidae and Personidae (often in Cymatidae in older literature): Tritons. Usually have thick, heavy, sculptured shells, though their beauty is often hidden by growth of their periostracum. Feed on echinoderms and molluscs. Fourteen species in Hawai'i. 

Charonia tritonis (Linnaeus 1767), the Triton's Trumpet (or Pu ole in Hawaiian). To twenty inches. . Indo-Pacific. Used by the Greek God Triton as well as Hawaiian and other indigenous folks as a blow horn. Important as a predator on Crown of Thorns Stars as well as other echinoderms. Hawai'i pic.  

Cowries, Family Cypraeidae

Cypraea species (not all...) Cypraea annulus Linnaeus 1758, the Gold Ringed Cowry (family Cypraeidae). A great animal for reef aquariums with algae to trim! Flattened top with bright golden rim... similar to the Money Cowry (C. moneta). Indian Ocean, Red Sea, to Central Pacific, including Hawai'i's leeward islands and the Cooks. To about half an inch in length. This one in my friend Maurice's tank at home!

Cypraea caputserpentis Linnaeus 1758, the Snakehead Cowry. Indo-Pacific, including Hawai'i. To about an inch and a half in shell length. This one off of Maui, Hawai'i.

Cypraea maculifera Schilder 1932, the Reticulated Cowry. Shallow water to fifty feet, in cracks and crevices, usually in caves. Common throughout its range in the Central Pacific. To 2 1/2". This one in Hawaii.

Cypraea tigris Linnaeus 1758, the Tiger Cowry. Too common as a "curio", this is no doubt the best know Cowry (or at least most recognized as a sea animal in the group). South Africa, Red Sea, Hawai'i, Society Islands. To four inches shell length. One off the Gilis, Lombok, Indonesia, another with a flashlight for size comparison where they "come the biggest", off of Hawai'i. 

Family Casididae: Helmets. Generally large shelled animals with a short spire (the upper end of shell whorls and apex). Helmet shells have a long aperture that sports a groove that the siphon lays in and protrudes. They feed on urchins, both heart and spiny ones... that the spines are of no concern. Four species in Hawai'i. 

Cassis cornuta (Linnaeus 1758), the Horned Helmut. One of four species found in Hawai'i. Common in shallow sandy environments. Found buried in sand with only whorls in evidence. Largest Hawai'ian Helmut (to 15"); used as a "blow horn" by natives in shows. Some authors believe specimens with fewer, higher horns are males, shorter, more numerous females. Kona pix. 

Family Conidae: (Superfamily Conacea, Toxoglossa). Predaceous species with a toxoglossal radula or none, associated with poison glands. The Cone Shells (Conus, Turris) and highly spired Terebridae (Terebra). Don't touch!

Conus abraeus Linnaeus 1758, the Hebrew Cone. Indo-Pacific. To 2 1/2" in length. Found exposed by day in sandy areas feeding on polychaete worms. Distinctive "Hebrew lettering" on heavy white shells. When alive the shell is covered with a yellowy periostracum. Kona photo. 

Conus marmoreus Linnaeus 1758, the Marbled Cone. Indo-Pacific. To 5" in length. Found at times exposed by day in sandy areas feeding on other cones. This is one of a few toxic/venomous cone species in Hawai'i. Cannot be handled anywhere safely.  Kona photo. 

Conus textile Linnaeus 1758, the Textile Cone. Indo-Pacific; Red Sea, much of the rest of the tropical Indo-Pac, including Hawai'i. Feeds on other prosobranch snails. Can be fatal to humans. Red Sea image.


Dendrodoris tuberculosa (Quoy & Gaimard 1832), the Tuberculous Nudibranch. Indo-Pacific. To six inches in diameter. Broadly roundish, flat in profile with rosette like structure over the dorsum. Reportedly produces substance/s that cause eye irritation if handled. Hawai'i (Kona) photo. Live in exposed rock areas with good sponge cover. 

Halgerda terramtuentis Bertsch & Johnson 1982, the Gold Lace Nudibranch. Hawaiian endemic. Michelle Lemech photo taken there.

Phyllidia varicosa. Red Sea to Hawai'i. To nearly three inches in length. In Hawai'i.  The latter about three inches in length. Hawai'i pix of a single individual and a pair. 

Phyllidiella pustulosa (Cuvier 1804). Black body with pink tuberculations arranged in rows to clusters. Common from the Red Sea to Hawai'i. One in Fiji, another in Hawai'i.

Pteraeolidia ianthina (Angas 1864). Sea Dragon. Mauritius, East Africa to Australia, Japan over to Hawai'i. To 15 cm. Photosynthetic via endosymbiotic zooxanthellae, harvested initially be eating hydroids. Indonesia and Hawai'i at right.

To: Part 1, Part 3Part 4,

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