www.Primo.com: About shellfish.

Understanding shells are general and have no biological significance but its use is widespread and used in economic activity.
In the broadest sense, means all the shells of mollusks with a shell (see Bivalvia). With this understanding, more appropriate to call the shellfish and clam commensurate with the meaning used in the United States. Examples of such usage can be seen in the term "craft of shells".
The word can also mean all the shells of shellfish that lives attached to an object. This includes all types of edible, such as blood clams and mussels (mussels Awung), but not including the types that can be eaten but sprawled on the sand or water base, such as seashell and mussels.
Shells are also used to refer to a variety of shellfish shells thick, chalky, with a radial pattern on the shell firmly. In this sense, green mussels are not included in it and is more properly called Kupang. Understanding the closest in English is a cockle.
In the most narrow sense, which is referred to as the shells are shells of blood (Anadara Granosa), a type of shellfish aquaculture which are common in the Indo-Pacific region, and many are sold in the shop or restaurant that sells seafood.

Common traits.

All shellfish have a pair of shell (also called grafting or valve) is usually connected to the mirror symmetry of a ligament (connective tissue). In most shells, there are two adductor muscles which regulate open-shell lid.
Shellfish do not have a head (also the brain) and the scallop only have eyes. Organ is owned by the kidneys, heart, mouth, and anus. Shells can move with "legs" that form a kind of flat organs removed from the shell at any time or by opening and closing the shell is startling.
Open circulatory system, blood vessels do not have the means. Blood oxygen supply comes from a very liquid rich in nutrients and oxygen that surrounds the organs.
The food is plankton shells, by means of filtering. The mussels themselves are prey for sharks and squid.
All shells are when young males. Some females will be in line with the maturity.
Shellfish have gonads, genital glands that produce sperm or egg shells depending on gender. Egg fertilization occurs externally where the sperm and egg meet in the water. Fertilized egg develops into a larva called trochophore, which will swim with the flow and stick it somewhere before it starts to form a shell.

Bivalves.

Bivalves are in a class of mollusks that includes all shellfish: has a pair of shell (called "bivalves" means two shells). Another name is Lamellibranchia, Pelecypoda or bivalve mollusks. Into this group includes a variety of shellfish, mussels, clams, gravestones, seashell, scallop, oysters, and clams; despite variations in bivalves is actually very broad.
Many shellfish useful in human life since ancient times. The flesh is eaten as a protein source. Shells used as jewelry, crafts materials, supplies grave, as well as means of payment in the past. Pearls are produced by several types of oysters. Modern use is also made of shellfish as a biofilter to pollutants.

Systematics.

The following classification is based on the classification of Newel (1965) based on morphology. Until now not available phylogeny that can be completely trusted. Some groups are known parafiletik, especially Anomalodesmata. There is also an alternative based on morphological systematics gills of Franc (1960) and mentioned as necessary in the list below. Franc separating Septibranchia in separate groups, although the molecular basis even make Eulamellibranchia be parafiletik.
Subclass Palaeotaxodonta (Protobranchia by Franc)
* Order Nuculoida
Subclass Cryptodonta (Protobranchia by Franc)
* Praecardioida
* Solemyoida
Subclass Pteriomorphia (oysters, mussels, etc.., Filibranchia according Franc)
* Arcoida
* Cyrtodontoida
* Mytiloida
* Ostreoida - initially including Pterioida
* Praecardioida
* Pterioida
Subclass Paleoheterodonta (Eulamellibranchia by Franc)
* Trigonioida
* Unionoida (types of freshwater mussels)
* Modiomorpha
Subclass Heterodonta (includes mussels, seashell, and the shells are commonly known, according Eulamellibranchia Franc)
† Cycloconchidae
† Hippuritoida
† Lyrodesmatidae
Myoida
† Redoniidae
Veneroida
Subclass Anomalodesmata ((Eulamellibranchia according Franc)
* Pholadomyoida

The body structure.

If observed, the shell is divided into two parts bound together by ligaments as strong and elastic fastener. These ligaments are usually always open, if disturbed, it will close. So, opening and closing the shell governed by ligament assisted by two kinds of muscles, namely the anterior and posterior parts. Looks concentric lines are parallel, the line is called a line menunjukkanmasa growth slow growth or no growth. This line berselangseling with ribbon growth shows rapid growth. The more lines and ribbon growth, then the older age of the animal. The oldest part of the shell is usually the thickest, prominent, located on the persendiaan called the umbo. In the posterior part of the shell there are two kinds of so-called slit chiffon. Cracks near the anus is called the siphon, to serve out the rest of the entry of water and Zatzat. Instead chiffon entrance is located at the lower part of which serves to siphon out the entry of oxygen, water, and food.

Shells Pelecypoda.

Shell / home Pelecypoda consists of the parts;
1. Periostrakum.
Periostrakum an outermost layer, formed from a substance called chitin konkiolin serves as a protector. If wet dark blue, brown when dry.
2. Prisma.
Prisma is a middle layer composed of calcite crystals.
3. Nakre.
Nakre known as mother of pearl layer is composed of a thin layer layer parallel and calcite (carbonate) that looks shiny.
4. Coat.
Mantle lies beneath nakreas consisting of cells nakreas (which
sekretnya nakreas forming layer and forming a pearl) connective tissue, and epithelial cells are ciliated.

Organ Systems.

Digestive system starts from the mouth, esophagus, stomach, colon, and anus. Mouth and anus is located in the mantle cavity. Excretion system uses a pair that functions as kidney nephridium. The nervous system consists of the brain, legs ganglion, and the ganglion muscle. Open circulatory system, the heart consists of a chamber and two porches. Respirasinya using gills.

Life Cycle.

VHewan there that are hermaphrodites and most of these animals have separate genitals. At the time of mating, the male genitalia will release sperm into the water and will be included in the body of a female animal. Through chiffon incoming water, so there was fertilization. Ovum will grow and evolve gills attached to the coat room, then exit the larvae will hatch and called glokidium. These larvae will come out of the female animal's body via siphon the water out, then the larvae attach to the gills or fins of fish and larvae will be wrapped by the skin mucus of fish. This is a parasite larvae for about 3 weeks. After growing up, the larvae will break away from the gills or fins of fish and will live free.

Image ;

So, thank you for reading this article. Written and posted by Bambang Sunarno.
sunarnobambang86@gmail.com
author:
http://schema.org/Personal.
https://plus.google.com/105319704331231770941.
name: Bambang Sunarno.
http://primadonablog.blogspot.com/2014/02/about-shellfish.html
DatePublished: February 13, 2014 at 15:25