BRACHIOPODS

Brachiopods

Brachiopods

Lingula Reevii

Lingula reevii is a brachiopod species known as the inarticulated brachiopod and is in the family Lingulidae. Inarticulated brachiopods have bilaterally symmetrical shells held together only by muscles and not teeth. The species is rare and is only known to occur in shallow, sandy reef flats in Kaneohe Bay, Oahu, Hawaii.

The shell is oblong oval, broadest in the middle, and rather narrow. The sides are very gently curved outwardly, the posterior edge tapers to a sharp point. The shell valves are moderately convex with a smooth surface. Color is blue-green or emerald and verdigris-green, especially along the middle. The lophophore consists of a fold of the body wall that possesses a crown of ciliated tentacles surrounding the mouth. The lateral cilia create a water current and fine plankton are transported down the tentacles to the brachial groove and into the mouth.

They burrow vertically in sand, leaving a three-hole siphonal opening at the surface. When disturbed, a rapid contraction of the pedicle pulls the animal below the surface and the siphonal openings are reduced to a slit. This species is capable of upward burrowing through a sediment layer, even if the animal has to autotomize (detach) the pedicle.

Lingula has separate sexes, and gametes are shed into the water column for external fertilization. Embryos develop into a free swimming larva that looks like a tiny adult; they develop a shell while planktonic. As additional shell material is laid down, the animal becomes heavy, sinks to the bottom, and takes up its adult existence. There is no metamorphosis in Lingula. The lifespan of Lingula spp. is estimated to be 5 to 8 years.

The species has declined in density from 500 per square meter in the 1960s to a maximum of 4 per square meter (Cindy Hunter, University of Hawaii, personal communication). The main threats are: 1) habitat degradation and alteration; 2) overexploitation; 3) marine pollution and sedimentation; 4) a vulnerable life history; and 5) a limited distribution.

The inarticulated brachiopod is a U.S. National Marine Fisheries Service Species of Concern,.[1] Species of Concern are those species about which the U.S. Government's National Oceanic and Atmospheric Administration, National Marine Fisheries Service,[2] has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species Act.[3]

Riftia Pachyptila

The association between Riftia pachyptila Jones, 1980 and its chemolitho-autotrophic, sulfideoxidizing (thiotrophic) endosymbionts was the first of this type of symbiosis to be described more than 20 years ago. Due to the high abundance at the hydrothermal vents of the East Pacific Rise, they are considered one of the most important ecosystem-structuring organisms in this habitat. They grow extremely fast and reach sizes of up to 1.5 meters.

Riftia pachyptila

Triphasic life cycle in vestimentiferan tube worms - a new approach in understanding their evolution

In this research project, the tubeworms are used as a model system for understanding the evolution of this type of thiotrophic symbiosis. Horizontal transmission of the symbionts is suggested to ...