What is the excretory system of mollusks?
Most mollusks have a basic excretory system. First, contaminants are filtered by a pair of nephridia, which are like kidneys. From there nitrogenous waste flows down canals to a bladder like sack.
Do mollusks excrete ammonia?
The vast majority of mollusks are aquatic and excrete nitrogen in the form of ammonia. In octopuses, however, nitrogen is excreted as ammonium chloride, which is quite strongly concentrated in the urine. Terrestrial snails and slugs excrete uric acid but may also excrete ammonia when living in moist surroundings.
What is an example of a mollusk?
A snail (Gastropoda) is probably one of the best known examples of a mollusk. Their excretory systems are capable of fully processing waste and excreting it as urine and feces. A squid (Teuthida) is another example of a mollusk. Contaminants are removed from the body and sent to the bladder.
How do snails excrete uric acid?
While water snails excrete ammonia, terrestrial snails' excretion produces uric acid, that crystallises on the septs' walls to form whitish crystals. This way the Roman snail only loses a minimal amount of water to dissolve the uric acid, which is finally excreted as a light brownish paste.
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What is the excretory organ of Mollusca?
metanephridiaThe organs of Bojanus or Bojanus organs are excretory glands that serve the function of kidneys in some of the molluscs. In other words, these are metanephridia that are found in some molluscs, for example in the bivalves. Some other molluscs have another type of organ for excretion called Keber's organ.
What type of digestive system does a mollusk have?
6. Clams (and all mollusks) have a complete digestive system. It consists of a mouth where food is ingested, a short connecting tube called the esophogus, a stomach which temporarily holds food, and an intestine where food digestion and absorption takes place.
What part of the mollusc body excretes the shell?
mantleThe mantle of mollusks and brachiopods secretes the shell in species that possess shells. It also forms a mantle cavity between itself and the body.
How do mollusks do gas exchange?
Basically all molluscs breathe by gills that are called ctenidia (comb-gills) because of their comb-like shape. In terrestrial molluscs this respiration organ is reduced, but still respiration takes place in the pallial cavity. That is why it is also called the snail's respiratory cavity.
How do clams get rid of waste?
The Excretory System of Clams And instead of an anus, clams have a body part called a siphon that opens to allows water (ingested during filter feeding) and waste products to exit the clam's body.
Which of the following structure helps in excretion and respiration in molluscs?
This is called the mantle cavity. The Mantle cavity houses feather-like gills. These gills serve both respiratory and excretory functions.
What does the mantle secrete in molluscs?
The mantle is a layer of tissue that lies between the shell and the body. It secretes calcium carbonate to form the shell. It forms a cavity, called the mantle cavity, between the mantle and the body. The mantle cavity pumps water for filter feeding.
Do mollusks have nephridia?
Molluscs also have a well-developed excretory system, using tubular nephridia organized as kidneys, that collect liquid wastes from the coelom and dump them in the mantle cavity, where they are pumped out of the shell.
How do molluscs reproduce?
Mollusks are primarily of separate sexes, and the reproductive organs (gonads) are simple. Reproduction via an unfertilized gamete (parthenogenesis) is also found among gastropods of the subclass Prosobranchia. Most reproduction, however, is by sexual means.
How do snails exchange gas?
The snails' gills look like a double comb, with a stem and feathery protrusions that are responsible for the general process of gas exchange: The absorption of oxygen from the water and the diffusion of carbon dioxide into the water. Those comb-like built gills are called ctenidia.
Do mollusks use diffusion?
Diffusion occurs through moist skin of the mollusks; they prefer to live in moist conditions. A mollusk has a heart, blood, and blood vessels. Oxygen and nutrients are carried to all parts of a mollusk's body by a circulatory system.
What type of respiratory system do mollusks have?
A ctenidium is a respiratory organ or gill which is found in many mollusks. This structure exists in bivalves, cephalopods, Polyplacophorans (chitons), and in aquatic gastropods such as freshwater snails and marine snails.
Mollusca
The phylum Mollusca is made up of the invertebrate organisms that we call mollusks. They are the largest marine phylum, making up 23% of all marine life, however there are also terrestrial mollusks as well. The phylum is extremely diverse and examples of these organisms could range from squids to snails. Most mollusks are snails or slugs.
Excretory System
Most mollusks have a basic excretory system. First, contaminants are filtered by a pair of nephridia, which are like kidneys. From there nitrogenous waste flows down canals to a bladder like sack. While there extra water is reabsorbed into the body.
Examples
A snail (Gastropoda) is probably one of the best known examples of a mollusk. Their excretory systems are capable of fully processing waste and excreting it as urine and feces.
Phylum Mollusca
Mollusca is the predominant phylum in marine environments, where it is estimated that 23 percent of all known marine species belong to this phylum. It is the second most diverse phylum of animals with over 75,000 described species.
VISUAL CONNECTION
Figure 1: There are many species and variations of mollusks; the gastropod mollusk anatomy is shown here, which shares many characteristics common with other groups.
CONCEPTS IN ACTION
Watch animations of clams and mussels feeding to understand more about bivalves.
Annelida
Phylum Annelida are segmented worms found in marine, terrestrial, and freshwater habitats, but the presence of water or humidity is a critical factor for their survival in terrestrial habitats. The name of the phylum is derived from the Latin word annellus, which means a small ring. Approximately 16,500 species have been described.
License
Introductory Biology: Evolutionary and Ecological Perspectives by Various Authors is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.
