What are infaunal bivalves?

What are infaunal bivalves?

Infaunal bivalves bury themselves into soft sand or sediment. Boring bivalves dig into wood or rock. Finally, the free-moving bivales use a muscular food to dig into soft sand and sediment.

What is epifaunal bivalve?

The molluscan Class Bivalvia (Class Pelecypoda or Lemellibranchiata of many authors) includes the clams, oysters, scallops, and similar groups, and is characterized by laterally paired external calcareous shells which enclose the soft parts, a highly modified foot which is large and adopted for burrowing in many forms.

Which type of bivalve has an infaunal lifestyle?

Clams prefer an infaunal lifestyle, buried in the sand or silt, whereas mussels, oysters, and scallops live a more epifaunal lifestyle (on or above the seafloor). Regardless of whether they’re in-ground or above-ground, they have specialized gills that serve two functions — to extract food and oxygen from the water.

What is special about bivalves shells?

The bivalve shell is composed of two calcareous valves. The mantle, a thin membrane surrounding the body, secretes the shell valves, ligament, and hinge teeth. The mantle lobes secrete the valves, and the mantle crest creates the other parts. The adductor muscles are what allow the bivalve to close the shell tightly.

What are characteristics of bivalves?

The bivalves are bilaterally symmetrical mollusks, enclosing the soft internal body. Common feeding characteristics of bivalves include filtering out particle food through an enlarged pair of gills known as ctenidia. Most bivalves are sedentary, but some use their foot to glide across substrate.

Why are they called bivalves?

Clams and their relatives (oysters, scallops, and mussels) are often called bivalves (or bivalved mollusks) because their shell is composed of two parts called valves. Bivalves have a long history.

What are the 5 groups of bivalves?

Bivalves as a group have no head and they lack some usual molluscan organs like the radula and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders.

What do bivalves use their foot for?

Like fish, bivalve mollusks breathe through their gills. As filter feeders, bivalves gather food through their gills. Some bivalves have a pointed, retractable “foot” that protrudes from the shell and digs into the surrounding sediment, effectively enabling the creature to move or burrow.

What are the 4 lifestyles of bivalves?

Bivalves make use of a variety of lifestyles. Sedentary species (e.g., mussels and oysters) spend their lives attached to a substrate , whereas others burrow underground (e.g., clams) or live on the water bottom and swim (e.g., scallops). Bivalves have highly reduced heads and simple nervous and sensory systems.

What are two characteristics of bivalves?

How are Bivalves adapted to live on hard surfaces?

Fig. 9.6 Bivalves living in hard substrates. Epifaunal bivalves exploit three living strategies: (i) attachment to the substrate by byssus threads; (ii) cementation to hard surfaces; and (iii) recumbent, free lying on the sediment surface stabilized by the shell morphology (Fig. 9.7).

What are the different types of bivalve shells?

Fig. 9.4 Bivalve morphology: (a) general interior of a valve (right valve), (b) general exterior of a valve (left valve), and (c) internal morphology. Arrows show water currents in the mantle cavity. Table 9.3 Types of bivalve dentition. Bivalve shells are multilayered.

Why are teeth important in a bivalve shell?

Teeth and sockets in the hinge area of the valves interlock to insure a tight fit when the shell is closed. Several patterns of dentition exist in bivalves, and this is a useful characteristic in classification. The main types are shown in Table 9.3. The earliest bivalves are known from Lower Cambrian rocks.

What was the role of bivalves in the Palaeozoic?

Groups arose with taxodont, dyso-dont, and heterodont hinges and a range of feeding strategies. Deposit feeders, byssally attached bivalves, and burrowers colonized marginal and nearshore environments. After this rapid radiation the group stabilized and bivalves were not a particularly diverse or abundant group during the Palaeozoic.