#pinnidae

[rattyexplores]

Bivalves! and their many forms

Although to many people these are nothing more than pretty shells, the truth of the matter, is that these were once all individual animals. Very primitive animals mind you.

Spondylus nicobaricus

Genus Lamarcka

Genus Gafrarium

Genus Spondylus

Genus Lioconcha

Barbatia amygdalumtostum

Family Pinnidae

15/06/22

[todropscience]

LA NACRA SE MUERE EN EL MEDITERRÁNEO ESPAÑOL

Investigadoras españoles del IEO recientemente han revelado las elevadas tasas de mortalidad -de hasta un 100%- en la mayor parte del litoral mediterráneo, incluyendo las poblaciones de Andalucía, Murcia, Comunidad Valenciana e Islas Baleares, mientras que las poblaciones de las costas catalanas todavía persisten. Se han realizado censos científicos en 137 localidades registrando datos de más de 1.600 nacras en distintos hábitats y en un amplio rango de profundidad. 

La presencia del parásito protozoo del género Haplosporidium que infecta la glándula digestiva es probablemente la causa esta mortalidad. Sin embargo en la actualidad aún se desconoce cuál ha sido la vía de entrada de dicho patógeno. La nacra (Pinna nobilis) es un molusco endémico y protegido del Mediterráneo que se caracteriza por ser el bivalvo más longevo y de mayor tamaño de este mar.  Las elevadas tasas de mortalidad han llevado a la comunidad científica a repensar el estado de vulnerabilidad de la nacra, a "en situación crítica" la que está pendiente de publicación en orden ministerial española. 

Referencia (Acceso Abierto): Vázquez-Luis et al.,  2017. S.O.S. Pinna nobilis: A Mass Mortality Event in Western Mediterranean Sea. Front. Mar. Sci.

[dozydawn]

20 completely non-nacreous pen pearls, from the group of 22 samples in this study, are set against a pen shell displaying both nacreous (left) and non-nacreous areas (right). Photo by Lhapsin Nillapat.

[todropscience]

This is a new bivalve species from Easter Island (in fact, the largest bivalve in the area). They live buried in sand and small pebbles, and are usually covered by a lot of other organisms.

Called  Pinna rapanui  this species is the 249th marine molluscan species found in Easter Island waters, and it is, by far, the largest bivalve species living around the island. A Polynesian origin of this species is suggested; however, its definite affinities with Indo-Pacific or South American fauna are still unknown.

Reference: Francisco Araya and Osorio. 2016. Pinna rapanui n. sp. (Bivalvia: Pinnidae): The Largest Bivalve Species from Easter Island, South Pacific Ocean, Chile . BioOne

Photo:  Juan Francisco Araya, who discovered the new species

[drhoz]

#711 - Pinna bicolor - Razor Clam

Large bivalves that occasionally wash up onto the beach. In this case, on Woodmans Point. The common name for them over here is Razor Clam, possibly because they are very narrow in profile, but the Pinnidae are also known as Pen Shells, Horse Mussels, and Fan Mussels. Razor Clam is confusing because there are much better recipients of that name on our shores - back over east it was applied to clams that resembled old-fashioned straight razors.

The genus has been around since the Cretaceous, and in the Mediterraneran the byssus threads were harvested to produce sea silk, an extraordinarily rare, fine, and valuable fabric. As an added bonus they occasionally produce pearls.