What is an example of Aplacophora?

What is an example of Aplacophora?

Among those there are the snails and slugs (Gastropoda), mussels and clams (Bivalvia), scaphopods (Scaphopoda) and squids, octopuses and cuttlefish (Cephalopoda). The bivalve shell only divided itself into two halves but later in evolution.
…
Shell-less Molluscs (“Aplacophora”)

Does Aplacophora have shell?

Aplacophora is a relatively small group of molluscs that are characterized by their lack of shells and worm-like appearance. Instead of a shell, their mantle secretes tiny calcareous spicules which give them a beautiful shine. There are only about 320 species of these exclusively marine molluscs.

What is the Mollusca symmetry?

Mollusks are generally considered a phylum of bilaterally symmetrical animals, although there are also many asymmetrical species. Bilateral symmetry means that an organism can only be divided into two equal halves if it is cut from top to bottom along the middle of the anterior-posterior (front-back) axis.

What makes Monoplacophora distinctive?

The main characteristics of Monoplacophora include (1) small, deep sea, almost bilaterally symmetrical; (2) have undivided arch shell; (3) body with distinct head and radula, without eyes or sensory tentacles (except around the mouth); (4) foot-retractor muscle; (5) anus median, posterior; (6) mantle cavity large.

What is the meaning of Aplacophora?

Definition of Aplacophora

: an order of Amphineura comprising wormlike mollusks in which the body is without calcareous plates but the mantle bears numerous calcified spicules over its entire surface.

What are 3 characteristics of Polyplacophora?

The main characteristics of Polyplacophora include (1) elongate or oval, dorsoventrally flattened, bilaterally symmetrical, marine; (2) with dorsal shell of eight plates embedded in a tough mantle; (3) mantle-edge stiffened (called the girdle); (4) large, muscular, ventral foot (girdle and foot can act as suction cup); …

Which body part is least developed in Aplacophora?

These mollusks are usually less than 2 in (5 cm) in length, but adult individuals may vary from 0.039–0.078 in (1–2 mm) to 3.9 in (10 cm) or more in length. The exterior of an aplacophoran may be spiny, smooth, or rough. The head is poorly developed, and the typical mollusk shell and foot are absent.

Is Mollusca asymmetrical?

In the phylum, Mollusca through there is bilateral symmetry, but it is lost in some forms, due to the phenomenon, called as. A. Asymmetry.

What are the characteristics of Mollusca?

Mollusca Characteristics

• They are mostly found in marine and freshwater.
• They exhibit organ system level of organization.
• Their body has a cavity.
• The body is divided into head, visceral mass, muscular foot and mantle.
• The head comprises of tentacles and compound eyes.
• The body is covered by a calcareous shell.

Which is an example of class Monoplacophora?

Although the shell of many monoplacophorans is limpet-like in shape, they are not gastropods, nor do they have any close relation to gastropods.
Monoplacophora.

What are examples of Scaphopoda?

DentaliumDentaliidaDentaliidaeGadilidaGadilidaeFissidental…
Tusk shell/Lower classifications

What makes Polyplacophora unique?

What is the meaning of Polyplacophora?

Definition of Polyplacophora
: an order of Amphineura comprising the chitons all of which have the foot occupying the whole ventral surface of the body and the shell composed of eight calcified dorsal plates.

How many species of Aplacophora are there?

Solenogastres (Aplacophora) is a small clade of marine, shell-less worm-molluscs with close to 300 valid species.

Do mollusks have radial symmetry?

Mollusks have an exoskeleton. Mollusks have radial symmetry.

What makes Mollusca unique?

A feature unique to molluscs is a file-like rasping tool called a radula. This structure allows them to scrape algae and other food off rocks and even to drill through the shell of prey or catch fish.

Is Mollusca a bilateral symmetry?

Mollusca can be found in freshwater, marine and terrestrial habitats. More features of molluscs include bilateral symmetry, soft or unsegmented bodies, respiration via ctenidium, ganglia/nerve comprised nervous system, haemocoel body cavity, etc.

Which of the following features is unique to Mollusca?

D Hard exoskeleton. The salient features of phylum Mollusca are: Soft and unsegmented body. Hard outer shell is present, may be internal (e.g. sepia) or external (e.g. snail).

What is the common name for Monoplacophora?

deep-sea limpets
The monoplacophora, common name (deep-sea limpets) are a small, but ecologically important group of single-shelled molluscs.

What are characteristics of Scaphopoda?

The scientific name Scaphopoda means “shovel foot,” a term that refers to the “head” of the animal, which lacks eyes and is used for burrowing in marine mud and sediments. The most distinctive feature of scaphopods is that the tubular shell is open at both ends, not just one end as in most molluscs.

Where are Scaphopoda found?

VIII SCAPHOPODA (TOOTH SHELLS)
Scaphopods are molluscs with a curved, tooth-like shell open at both ends. Scaphopods occur in the benthos of both shallow and deep waters of all major seas (McFadien-Carter 1979). The narrow end of the shell often protrudes above the mud or sand in which the animal lives.

What is a Bidarki?

“Bidarki” is a common name for species of chiton that is common in suitable rocky intertidal habitat of Southcentral Alaska. This name reflects the history of the area: “bidarki” is the Russian word for the type of boat that that the animal resembles when it curls up into a defensive half-circle.

Is Aplacophora a class?

Aplacophora /æpləˈkɒfərə/ is a presumably paraphyletic taxon. This is a class of small, deep-water, exclusively benthic, marine molluscs found in all oceans of the world. All known modern forms are shell-less: only some extinct primitive forms possessed valves.

What type of symmetry do starfish have?

These three challenges revealed that starfish have a hidden bilateral symmetry, and move in a preferred direction. That’s especially obvious when they face stressful situations, such as fleeing or having to turn themselves over.

Do all mollusks have bilateral symmetry?

Most mollusks have well-developed nervous systems with large brains and sense organs. Most of these animals have a closed digestive system with only one opening, and a true coelom. All animals of the phylum Mollusca have bilateral symmetry.