Megathura crenulata

Megathura crenulata
	Megathura crenulata on the right, and the warty sea cucumber Parastichopus parvimensis on the left
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Vetigastropoda
Order:	Lepetellida
Family:	Fissurellidae
Subfamily:	Diodorinae
Genus:	Megathura
Species:	M. crenulata
Binomial name
	Megathura crenulata; Sowerby I, 1825

Last updated June 04, 2024

Living specimen of Megathura crenulata with mantle extended over much of its shell. GiantKeyholeLImpet.JPG — Living specimen of *Megathura crenulata* with mantle extended over much of its shell.

Megathura crenulata is a northeastern Pacific Ocean species of limpet in the family Fissurellidae ^[1] known commonly as the great keyhole limpet^[2] or giant keyhole limpet.^[3]Megathura is a monotypic genus; in other words, this is the only species in that genus. This species occurs along the rocky coast of western North America, its distribution extending from Southern California to the Baja California peninsula in Mexico. It is found in the intertidal zone and in the sea up to a depth of 33 meters.^[3]

Description

Limpets of this family have a hole at the top of the shell, the portal through which waste products are released. This makes them different from the true limpets, which release waste from the mantle beneath the shell. This species is one of the largest keyhole limpets.^[4]

Biology

This species consumes a varied diet of plant, animal, protist, and algal material. It has been noted to consume filamentous cyanobacteria, diatoms, brown and red algaes such as seaweeds, seagrass, forams, hydrozoans, bryozoans, nematodes, bivalves, gastropods, crustaceans, and tunicates. The larger part of its diet is composed of brown and red algae, tunicates, hydrozoans of the genus Eudendrium and bryozoans of the genus Crisia .^[5]

M. crenulata has been used for experimental studies on gamete agglutination. Its blood contains a hemocyanin that appears blue due to its copper content. This protein carries oxygen as hemoglobin does in vertebrates. Unlike hemoglobin, the hemocyanin is not bound to cells but is simply dissolved in the hemolymph, the fluid part of the blood.^[6]^[7]

Keyhole limpet hemocyanin

Keyhole limpet hemocyanin from Megathura crenulata is used as vaccine carrier protein. Keyhole limpet hemocyanin (KLH) is a copper containing respiratory protein, similar to hemoglobin in humans. KLH is a large protein that acts as the hapten carrier part of the vaccine component, and is so far thought to be non-toxic. The major potential use of KLH is for bladder carcinoma by stimulating a specific immune response, but there are many other medical uses such as stress assessment, understanding inflammatory conditions, and treating drug addiction. Vaccines and other KLH uses are in the research or trial phases. A liter of blood from a keyhole limpet will produce 20 grams of protein, which can be worth as much as $100,000.^[8]^[9]^[10]

Related Research Articles

<span class="mw-page-title-main">Hemocyanin</span> Proteins that transport oxygen throughout the bodies of some invertebrate animals

Hemocyanins (also spelled haemocyanins and abbreviated Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O₂). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not confined in blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form.

An immunogen is any substance that generates B-cell (humoral/antibody) and/or T-cell (cellular) adaptive immune responses upon exposure to a host organism. Immunogens that generate antibodies are called antigens ("antibody-generating"). Immunogens that generate antibodies are directly bound by host antibodies and lead to the selective expansion of antigen-specific B-cells. Immunogens that generate T-cells are indirectly bound by host T-cells after processing and presentation by host antigen-presenting cells.

The Patellogastropoda, common name true limpets and historically called the Docoglossa, are members of a major phylogenetic group of marine gastropods, treated by experts either as a clade or as a taxonomic order.

Fissurellidae, common name the keyhole limpets and slit limpets, is a taxonomic family of small to medium-sized limpet-like sea snails, marine gastropod molluscs in the clade Vetigastropoda.

Diodora cayenensis, the Cayenne keyhole limpet, is a species of small to medium-sized sea snail or limpet, a western Atlantic marine prosobranch gastropod mollusk in the family Fissurellidae, the keyhole limpets.

Keyhole limpet hemocyanin (KLH) is a large, multisubunit, oxygen-carrying, metalloprotein that is found in the hemolymph of the giant keyhole limpet, Megathura crenulata, a species of keyhole limpet that lives off the coast of California, from Monterey Bay to Isla Asuncion off Baja California.

Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage. Taxonomically the Vetigastropoda are sometimes treated as an order, although they are treated as an unranked clade in Bouchet and Rocroi, 2005.

Fissurella volcano, commonly named the volcano limpet or volcano keyhole limpet, is a species of small to medium-sized sea snails, marine gastropod mollusks in the family Fissurellidae, the keyhole limpets. Like other members of the keyhole limpet family, the volcano limpet is not considered a "true" limpet.

Diodora aspera, also known as the rough keyhole limpet, is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets. Although similar in appearance to a common limpet, it has a hole near the apex of its shell, and is only distantly related. It often has a scaled polychaete worm Arctonoe vittata living inside its shell as a commensal. In the event that it is attacked by a starfish, it extends flaps of mantle to defend itself, and the worm also helps drive the predator away.

Diodora canariensis is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets.

Diodora funiculata is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets.

Fissurella barbadensis is a species of limpet in family Fissurellidae, the keyhole limpets. It is known commonly as the Barbados keyhole limpet and the rugose slit limpet. This species is native to the western Atlantic Ocean, including many islands of the Caribbean.

<i>Puncturella exquisita</i> Species of gastropod

Puncturella exquisita is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets.

Diodora jukesii, common name Jukes' keyhole limpet, is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

Puncturella cucullata, common name the hooded keyhole limpet, is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

<i>Puncturella pelex</i> Species of gastropod

Puncturella pelex is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

Puncturella cumingii is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

Fissurella crassa, common name the thick keyhole limpet, is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

Fissurella virescens, also known as the green Panama keyhole limpet, is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

The Diodorinae, common name keyhole limpets and slit limpets, is a taxonomic subfamily of limpet-like sea snails, marine gastropod molluscs in the family Fissurellidae, the keyhole limpets and slit limpets.

References

↑ Rosenberg, G. (2015). Megathura crenulata (Sowerby I, 1825). In: MolluscaBase (2015). Accessed through: World Register of Marine Species on 16 February 2016.
↑ Megathura crenulata. Hardy's Internet Guide to Marine Gastropods.
1 2 Megathura crenulata. SeaLifeBase.
↑ Family: Fissurellidae (Keyhole Limpets). Gladys Archerd Shell Collection, Washington State University Tri-Cities Natural History Museum.
↑ Mazariegos-Villarreal, A., et al. (2013). Diet of the keyhole limpet Megathura crenulata (Mollusca: Gastropoda) in subtropical rocky reefs. Journal of Shellfish Research, 32(2), 297–303.
↑ Castro, P. and M. Huber. Marine Biology. 8th ed. McGraw-Hill/Irwin
↑ Morris, R. H., D. P. Abbott, and E. C. Haderlie. Intertidal Invertebrates of California. Stanford, CA Stanford UP, 1980. Print
↑ Harris, J. R. & Markl, J. (1999). Keyhole limpet hemocyanin (KLH): a biomedical review. Archived 2016-02-24 at the Wayback Machine Micron, 30(6), 597–623.
↑ Sommer, L. Harvesting blood from limpets for a cancer vaccine. IEEE Spectrum 28 September 2012.
↑ Roudman, S. How mollusk blood could cure cancer. Popular Science 30 December 2011.