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Family Pectiniidae: (Gk. pectinis, comb).... probably relating to the comb-like appearance of the walls, which are often tall, thin and striated. In general morphology, pectiniid colonies are usually laminar, composed of thin plates of varying thickness. The family is characterized by thick fleshy, sometimes colorful, polyps which have a superficial resemblance to some faviids and mussids. Corallites, which are visible to the naked eye, are highly visible and prominent, do not have definite walls (but if present are only rudimentary, and are formed by the nonporous costate coenosteum of the laminae (Veron 1986). There seems to be some variation in the strength of the corallum within and among species, depending on environmental conditions. Most members of this family are usually found of reef slopes and off-reer floor.

There are five extant genera (i.e. Echinophyllia, Echinomorpha, Oxypora, Mycedium and Pectinia) all found in PNG waters. The fossil record is poor; affinities with the Mussidae, which seem clear, are primarily based on skeletal morphology. There is stronger latitudinal attenuation of combined species of the family down the eastern and western coasts of Australia than in Japan due to differences in species compositions. Along all three coastlines, attenuation becomes very pronounced with abundance data.
Colonies of Mycedium elephantotus were observed to be thicker and sturdier on reefs where strong currents presominate, and where tidally-induced upwelling events are common (i.e. daily phenomena). According to most sources, the polyps are expanded only at night, when the animal presumably feeds. However, it was observed that juvenile colonies of Mycedium elephantotus were feeding also during the day. These colonies were situated near a hydrothermal vent, where temperatures reached 42C.


Some members of the family Pectiniidae (131kB)

Pectiniidae can be found in a variety of habitats, from shallow upper reef slopes to deeper fore-reef slopes, as well as from clear offshore habitats to fringing reefs in turbid coastal waters. The general morphology of the corallum makes most pectiniids highly efficient passive sediment rejectors. Their abundance, especially of Pectinia spp. in turbid coastal areas, may be directly related to their sediment-rejection ability.
All pectiniidae studied thus far are hermaphroditic and spawn gametes. Echinophyllia aspera, E.orpheensis, Mycedium elephantotus, Oxypora glabra, Pectinia alcicornis, P.lactuca, and P.paeonia have been observed to spawn during mass-spawning events.

Key to the family Pectiniidae Corallites are more conspicuous than coenostial structures
Non-colonial: Genus Echinomorpha
Colonial genera Coenostial pits present: Genus Oxypora
Coenostial pits absent Corallites not inclined: Genus Echinophyllia
Corallites inclined: Genus Mycedium
Coenostial structures very conspicuous: Genus Pectinia
All genera are only found in Indo-Pacific waters:------------------------------------------------------------------------------

Echinophyllia (Gk. echinos, hedgehog, spiny; phyllon, leaf):

Low-growing corals with irregular foliaceous or encrusting growth form. Center of corallum is attached and solid. Margins are free and thinner. Colonies are brown, with the calices green or pink. Corallites which are scattered in a pattern of concentric rows, are prominent and are often separated by a gap of several mm or more. Corallites may be 10-20mm in diameter and are generally elevated several mm above the surface of the corallum (plocoid). Calices are roundish in cross section, and connected with neighborung calices by numerous and exsert septa. Paliform lobes are usually present with elaborately worked dentate costal margins.
PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific.
GENERAL ABUNDANCE: very common, conspicuous.
FOSSIL RECORD: Miocene of the Indo-Pacific.
NUMBER OF EXTANT SPECIES: 8 known species.
Echinomorpha (Gk. echinos, hedgehog, spiny; morphus, figure, shape): Due to the large corallites, its overall rarity and skeletal characteristics, a separate genus was created for the only member in this family E.nishihirai, formerly placed in Echinophyllia (Veron 2000). This species predominantly occurs as a solitary individual which are thin and delicate. Corallites of colonial individuals are very large. Skeletal characters include mussid-like septal teeth and Echinophyllia-like pattern of costae.
PRESENT DISTRIBUTION: central Indo-Pacific (Malaysia, Indonesia, Phillipines) and Southern Japan.
GENERAL ABUNDANCE: rare but distinctive.
NUMBER OF EXTANT SPECIES: 1 known species.
Oxypora (Gk. ox, sharp; porous, pore): Semi-encrusting with free-foliaceous margins. Brittle and fragile corallum, with a warty appearance; colonies are brown in color with pink, green, or gray calice centers. Spider-like corallites are well separated and distinct, others are crowded and partially joined together. The coenosteum is perforated with grooves. Calices are rounded to elliptical in shape (3-8mm in diameter) and are superficially or slightly raised. Each calice houses 8-12 septo-costae that are thickened and exsert at the outer edge. Costae and septa have sharp spines.
PRESENT DISTRIBUTION: Western Indian Ocean to southern Pacific.
GENERAL ABUNDANCE: generally common, conspicuous.
FOSSIL RECORD: Pliocene of the Pacific.
NUMBER OF EXTANT SPECIES: 5 known species.
Mycedium (Gk. mykes, knobbed; -idion, diminutive suffix): Foliaceous or semi-encrusting colonies that may measure 2m across. Edges tend to be delicate and easily broken; colonies are brown with pink or greenish tinges and brightly colored green or red oral disks. Coralites are well spaced, crowded in places with diameters ranging 5-15mm and inclied, facing outwards to the edge of the colony margins. Sometimes they protrude 3-4mm from the corallum. Septa are numerous with sharp spines and continue as costae on perithecal areas. Costal margins are spiny.
PRESENT DISTRIBUTION: Red Sea and western Indian Ocean to southern Pacific.
GENERAL ABUNDANCE: generally common, conspicuous.
FOSSIL RECORD: Miocene of the Tethys.
NUMBER OF EXTANT SPECIES: 5 known species.
Pectinia (Gk. pectinis, comb): Forms encrusting, foliaceous, or branching colonies with a distinct semi-meandrine arrangement of collines which form thin, delicate convulated leaves (or even fluted walls) over the surface of the corallum (up to 5cm high and few mm wide). Calices are superficial and lack true walls, circular and oval inappearance (2-10mm in diameter), are widely spaced and scattered over the coral surface. Colony color is brown, or gray with green tints on top; top of the walls are pale. Margins of septa and septo-costae are finely and irregularly serrated.
PRESENT DISTRIBUTION: western Indian Ocean to southern Pacific.
GENERAL ABUNDANCE: generally common, very conspicuous.
FOSSIL RECORD: Pliocene (?) of the Pacific.
NUMBER OF EXTANT SPECIES: Approximately seven. 9 known species.