Venerida

Venerida is an order of bivalve molluscs that live in saltwater or freshwater habitats.
They have two shells that are usually thick and equal in size, with three teeth on the hinge that connect them.
They are mostly filter feeders that use siphons and gills to obtain food and oxygen from the water.
They include many edible clams that are harvested for human consumption, such as the hard clam or quahog.
Some of them can also produce pearls or have colorful shells that are used for jewelry or decoration.
Venerida is a diverse and widespread group of animals that have been around since the Paleozoic era.

The Venerida are an order of mostly saltwater but also some freshwater bivalve molluscs.
They live in various marine and brackish habitats, such as sandy or muddy bottoms, coral reefs, seagrass beds, and estuaries.
Some species can also tolerate low salinity or even freshwater conditions, such as the Cyrenidae and Glauconomidae.

The Venerida include many familiar groups, such as many clams that are valued for food and a number of freshwater bivalves.
Some of the most important edible species are commonly known as "clams", such as the hard clam or quahog, Mercenaria mercenaria.
The Venerida are characterized by having three main hinge teeth in each valve, a well-defined anterior area called the lunule, and a posterior external ligament.
They also have a folded gill structure adapted for filter feeding.

The Venerida are one of the most diverse and abundant orders of bivalves, with over 500 living species and many fossil forms.
They have a worldwide distribution, but are especially diverse in tropical and subtropical regions.
The Venerida have a long evolutionary history, dating back to the Ordovician period.
They have undergone several taxonomic revisions, based on morphological and molecular data.

Venerida are mostly saltwater clams, but some of them can live in freshwater habitats.

They are filter feeders, using paired siphons and folded gills to obtain food particles from the water.

Many of them are edible and exploited as food sources.

Some of the most important commercial species are the hard clam or quahog, Mercenaria mercenaria, and the Pitar clams.

Venerida are classified into several subfamilies and genera, based on their morphological and molecular characteristics.

However, the taxonomy of this group is still controversial and subject to changes.

Some common species have been moved between different genera or subfamilies, as new evidence emerges.