Related FAQs: The Fishes of the Red Sea,  Related Articles: Reef Flats, Reef Slope,  Biotopes, Fishwatcher's Guide to the Red Sea, Triggerfishes of the Red Sea, Butterflyfishes of the Red Sea, Angelfishes of the Red Sea,   Marine Aquarium Biotopes: Pt.3 Sandy Red Sea Reef Slope 3 of 5
Bob Fenner

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Stony Corals, Order Scleractinia: play a minor role here. There are occasional stands of acroporids, either branching Acropora or more demure encrusting colonies of Montipora, but these are the exception rather than dominant organisms. Occasionally one of a few Goniopora species will dominate a bommie, coral rock area. 

Acropora hemprichii (Ehrenberg 1834), family Acroporidae. Irregularly branched with radial corallites as open thickets, large, round, upright, conical. Axial corallites common, prostate, of thick smooth walls. Most are brown to pink in color, some blue. Red Sea images.

Goniopora columna Dana 1846, family Poritidae. Colonies as tufts on short columns. Corallites vary depending on position. Ones toward the center of colonies have fine columella and septa; those on the side more robust structures. Polyps have large central cones. Indo-Western Pacific. Queensland close-up and Red Sea images.

Goniopora lobata Milne Edwards and Haime 1860. Colonies as columns with growth. Large (more than 5mm.) corallites with small columellae and oral cones; elongate in appearance on full extension. Tentacles and oral cones typically white in color; contrasting with polyps which are otherwise brown, tan or green. Below left in Queensland, Australia., and broken and whole colonies in the Red Sea.

Favia laxa (Klunzinger 1879), family Faviidae. Hemispherical colonies whose corallites are conical, showing both extra- and intertentacular budding. Paliform lobes look like an internal crown. Fine line of demarcation between costae. Pale to pinkish brown in color. Common in the Red Sea where this picture was made.

Favia stelligera (Dana 1846), family Faviidae. Colonies of round to columnar/colonial in appearance, sometimes a few meters across. Uniform septa and walls (not shared). Brown to green in color. Red Sea upper gulf photos.

Galaxea astreata Lamarck 1816. Generally smaller corallites than G. fascicularis (3-5 versus 10 millimeter diameter), an important characteristic as these are the two common species of this genus and their extensive ranges overlap greatly. Tentacles usually only out at night. A close-up of a small colony in Cebu, P.I.

Galaxea fascicularis Linnaeus 1767). Captive colonies are ball-shaped, in the wild more like low-lying cushions that may extend meters over the bottom. Corallites well-separated with blade-like septa that may rise more than a cm. above the corallite wall. Occur in grays, greens and browns. Transparent tentacles out during the day, generally with contrasting colored tips. Here in the Red Sea.

Plerogyra sinuosa (Dana 1846), family Euphylliidae (formerly Caryophylliidae). Flabello-meandroid skeleton as shown, with grape-like variable vesicles that are slow to retract (but still can/do sting). Typically found in turbid water. Below: Skeleton close-up a small and large colony in the Red Sea.

Sea Anemones, Order Actinaria, occur throughout the Red Sea at moderate depths. There are three principal species that are mutuals of the single species of Clownfish found here (and occasionally a batch of Dascyllus). Occasionally you may find a "Pizza Anemone". If so, do look closely for its commensals.

Heteractis magnifica (Quoy & Gaimard 1833), the Magnificent Sea Anemone. Found in open areas, attached to a solid object. Base of solid purple, blue, green, red, white or brown color. Oral disc flat with barely tapering, finger-like tentacles up to a meter across. Specimen at Anemone City, Ras Mohamed at right engulfed in a wash of Dascyllus trimaculatus.

Heteractis crispa (Ehrenberg 1834), the Leathery Sea Anemone. Often mis-sold/identified in the trade as H. ritteri and the commonest species in the market as the "Sebae Anenome". Has numerous long, tapering tentacles that end in points. Column gray in color. A specimen in the Red Sea.

Entacmaea quadricolor (Ruppell & Leuckart 1828), the Bubble-Tip or Bulb-Tentacle Sea Anemone.  This is historically the hardiest of large, naturally symbiotic Clownfish anemones for aquarium use... many more specimens are collected and received in tact, in reasonably good health from the wild to distributors. A colonial grouping and a close-up image of the Bubble-Tip Anemone and the Clownfish, Amphiprion bicinctus in the Red Sea.

Cryptodendrum adhaesivum Klunzinger 1877, the Adhesive Sea Anemone, aka as the Pizza Anemone for obvious reasons. Not often seen, used in the aquarium interest due to the species extremely sticky short tentacles and propensity for tearing in moving. Only one Clownfish species is found in it in the wild, the Clarkii. Red Sea image and commensal "Sexy Shrimp", Thor amboinensis

Worms of Many Kinds, but particularly the Polychaete Annelids mainly knowns as "bristleworms" to aquarium hobbyists exist in good numbers of individuals and species in the Red Sea. Other worm groups, worm-like animals exist here in abundance; Peanut Worms (phylum Sipuncula), Tongue Worms (phylum Echiura), Ribbon Worms (phylum Nemertea), Acorn Worms (phylum Hemichordata), but these are rarely encountered by aquarists, or divers, unless they're digging about, searching for them. 

Molluscs: We've mentioned the Giant Clams, family Tridacnidae above. There are some notable, common bivalves as well:

Limaria fragilis Gmelin 1791, the Fragile File Shell. Indo-Pacific; Red Sea to Japan, Australia. Takes a beating if stocked with many types of fishes, crustaceans. Needs to be inserted in rock cover. Need frequent "immersion type" feedings... daily. Queensland, Australian photo.

Crustaceans exist in all marine environments in the Red Sea, and the Sandy Slope and beneath it are no exceptions. There are twenty plus species of Stomatopods (Mantis Shrimp) for instance; though the few species utilized in ornamental aquatics rarely are collected here. The principal species utilized are the commensal and mutual shrimp species largely gathered elsewhere. There are many true Crabs here, but most hobbyists resist housing these opportunistic omnivores for fear they'll eat there other livestock. 

Periclimenes longicarpus Red Sea, Arabian Sea endemic. Usually associated with the Bubble Tip Anemone, Entacmaea quadricolor, here on a Bubble Coral, Plerogyra sinousa. There are at least 45 species of commensal shrimps of the subfamily Pontiinae in the Red Sea.

Thor amboinensis (de Man 1888), the Squat Anemone or Sexy Shrimp (in reference to its usually-raised tail). 1/4-3/4" long. Common in all tropical seas. Found in association with Giant, Sun, Elegant Anemones. Here is a pair (female larger) in a Pizza Anemone, Cryptodendrum adhaesivum.

Snapping Shrimps, family Alpheidae. Noted for their noise making capacity, myths re the power of their large claw (a .22 caliber, tank-cracking...) and commensal to mutualistic relationships with fishes (mainly Gobies) and invertebrates. At least ninety five species are recorded from the Red Sea.

Hermit Crabs, infraorder Anomura. There are about four dozen species of Hermits in seven families described from the Red Sea. Most are of dubious value (to destructive) in marine, especially reef aquariums. I'll list a few of the more commonly encountered in the trade that can be found here.

Trizopagurus strigatus (Herbst 1804), the Striped or Halloween Hermit Crab. Indo-Pacific and Red Sea. To a little over two inches in length. Nocturnal. Lives in empty Cone shells. Feed on live and dead animal material.

Dardanus tinctor, a Coral Hermit Crab. This one with its Calliactis polypus Anemones out at night in the Red Sea. To 10 cm. Large left claw. Nocturnal; omnivorous. Moves anemones when transferring to new shells.

Dardanus lagopodes (Forsskal 1775), the Blade-eyed Hermit Crab. Indo-Pacific, including the Red Sea. To a little over two inches in length. White eye stalks, body mottled in maroon, brown, covered with white-tipped bristles. This one in Aitutaki, Cook Islands.

Spiny Skinned Animals, phylum Echinodermata. The Red Sea Sandy Slope has a number of echinoderms, but most are either too touchy or too large for aquarium use. One Sea Cucumber that is found here does make it into the trade.

Holothuria edulis Lesson 1830, the Edible Sea Cucumber (no thanks, I'm full). Indo-Pacific; Red Sea to Hawai'i. Lives in the open, on sand, seagrass beds, under rocks. Substrate licker. To one foot in length. Aquarium and Fiji images.

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