Extreme pH conditions at a natural C02 vent system (Italy) affect growth, and survival of juvenile pen shells (Pinna nobilis).
Relative growth rates of the noble pen shell Pinna nobilis throughout ontogeny around the Balearic Islands (Western Mediterranean, Spain).
There are giant clam shells (Tridacna gigas) from Palawan province and amber pen shells
(Pinna carnea) from Sorsogon.
In these flats, cowries, cones, mitres, turrids, bubble shells, pen shells
, cockles and scallops all living in close proximity and even the most delicate shells may survive intact.
Tokyo, Japan, June 6, 2006 - (JCN) - The Fisheries Research Agency (FRA) has undertaken a research project of pen shells
, a kind of clam dwelling in Ariake Sea.
Stretching along the gulf north of town, these white sand beaches hold the greatest variety and quantity of discoveries we found: scallop-edged yellow cockles, wing-shaped zebra arks, nearly translucent fig shells, fighting conches, stubby branched sponge's, sea stars, stiff pen shells
, pear whelks, lightning whelks, and the papery spirals of their egg cases.
The number and size of released and fertilized eggs and the survival of larvae were higher in pen shells
collected at 5-8 m depth, compared with those collected at less than 1 m.
Joseph Bay and Alligator Harbor, horse conchs were seen feeding primarily on other gastropods and pen shells
(Paine 1963a, Kuhlmann 1994), tulip snails fed on a greater variety of organisms (including gastropods, bivalves, worms, and carrion (Paine 1963a)), and whelks consumed mostly bivalves (Paine 1963a, Kent 1983b).
The pen shells
of the family Pinnidae are commercially important in a number of Indo-Pacific countries.
live partially buried upright in the sand, anchored by their numerous byssus filaments to the rhizomes and shoots of P.
These results suggested that gonad development of pen shells
in suspension culture was characterized by annual synchronicity in males and females, a spawning period from May to September resulting from monocyclic gametogenesis throughout the year, and an inverse relationship between gonad development and glycogen level.
The data indicate that pen shells
of form G and form Y are similar not only among individuals within the same form, but also between individuals from the two forms, and that shells of form T and form S are highly divergent.