In our article you will find answers to questions about how mollusks eat, what is common in the diet of lancelet and mollusk. These organisms are not accidentally compared. They have many common features, many of which relate to physiological processes.
Lancelet and mollusk: aquatic inhabitants
Lancelet is the most primitive animal of the Chordata type . But his position in the system of the organic world was not easy to determine. Scientists mistook him for a clam and called it a lanceolate slug. Only 60 years after the discovery of this animal, it became known that they are a representative of a completely different type. Indeed, the appearance of lancelet and mollusk is very easy to confuse. They have a soft body that is not segmented. But at the lancelet, an axial skeleton called the chord is located inside. Mollusks are deprived of it.
What is common in the nutrition of mollusks and lancelettes? First of all, it is a single habitat in which they mine it. These organisms live in water. Lancelet prefers shallow seas. He leads a semi-mobile lifestyle, with one end of his body buried in the sand.
Depending on the species, mollusks can live in the seas, fresh water, on land. For example, a grape snail, which is a representative of the gastropod class, can be found on forest litter. But cephalopods live exclusively in the seas and oceans. To bivalves include toothless, perlovka, draysen, mussels, oysters, shipworms, tridact. They live only in bodies of water.
What is common in the nutrition of shellfish and lancelet
According to the method of nutrition, the lancelet has the most similarities with representatives of bivalve mollusks. Gastropods scrape off algae from the substrate. They do this with a grater - a tongue covered with horn denticles. But cephalopods are active predators. They attack fish and crustaceans.
Primitive chordates are not adapted to this. What is common in the diet of lancelet and bivalve mollusks? All of them are heterotrophs that absorb suspended organic particles from water. These are also called filtrators.
Digestive system
To find out what is common in the nutrition of lancelet and mollusks, it is necessary to consider the structure of the digestive system. She is a cross-cutting type. In the lancelet, the digestive system is represented by the through intestine, which forms the hepatic outgrowth. It begins with a mouth opening surrounded by tentacles. The next section is the pharynx penetrated by gill slits.
In mollusks, the digestive system also begins with the mouth and ends with the anal. The latter opens into the mantle cavity. The middle section of the intestine forms an expansion called the stomach. Another example that shows what is common in the diet of lancelettes and mollusks is the presence of specialized glands. In the former, they are represented only by the liver. And mollusks also have salivary glands, the ducts of which open in the throat. The composition of this substance in different classes may vary. For example, in cephalopods, in addition to enzymes, saliva contains toxins that kill prey.
Source of power
What else is common in the diet of lancelet and bivalve mollusks? This is the food itself. Since it enters the body through filtration, it contains microorganisms, blue-green algae, ciliates, small crustaceans, eggs and larvae of other animals. All of them form the basis of zoo and phytoplankton. Minerals that are dissolved in water are also absorbed by organisms. This way of eating is passive. In many ways, it was he who determined the sedentary lifestyle of the lancelet and bivalve mollusks.
Filtrators
The most important feature that determines what is common in the diet of lancelettes and mollusks is, of course, filtration. For its implementation, mollusks have siphons. These are two holes in the back of the body that open into the mantle cavity. Water flows with particles of food suspended in it through the lower siphon. And through the top stands out already in its purest form.
Lancelet filtration is closely related to respiration. Cilia located in the pharynx and on the partition between the gill slits create a constant flow of water. Gas exchange also takes place here.
So, we examined what is common in the diet of lancelet and mollusk. These animals have similarities in the general plan of the digestive system. She is a cross-cutting type. It consists of a tubular differentiated intestine, as well as digestive glands. The organisms that we examined in our article are heterotrophic filtrators. They feed on organisms suspended in water, which they pass through themselves. This method is passive, causing a sedentary lifestyle of these animals.