There are about 15, species in this phylum. The phylum includes earthworms, leeches, and marine worms known as polychaetes. Species in this phylum have metameric bodies. Segmented Bodies Metameric bodies are divided into segments called annuli. The annuli are covered in tiny hairs called setae. Setae help the worms move. Mollucs 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.
Mariela Ashfaq Pundit. What is the excretory unit of earthworm? Fluid from the excretory tubules leaves the body through pores. In earthworms , members of the phylum Annelida, the excretory system consists of structural units called nephridia the singular is nephridium. Saeid Toba Pundit. Do worms sleep? Do Worms Sleep? If sleep is defined as a period of inactivity, then worms indeed sleep. So Yes and No. Orion Bugarin Pundit. Why does a worm have 5 hearts? In the worm world, these wonderful earth loving creatures have five blood pumping organs in their tiny, hard working bodies.
But the worms ' hearts do not fill up with blood the way humans do , they just squeeze the two blood vessels which help to circulate the blood through out the body. Herculina Borgart Pundit.
Do worms have a face? Worms find each other usually in moist conditions where food is abundant. Conditions must be just right or worms will not reproduce for fear that their babies will not survive.
Worms face each other in a juxtaposing position. Emir Dehiya Teacher. Do worms have genders? Earthworms are hermaphrodites; that is, they have both male and female sexual organs.
The sexual organs are located in segments 9 to As a result, segment 15 of one worm exudes sperm into segments 9 and 10 with its storage vesicles of its mate. Rachael Martidi Supporter. Water then enters the tubules via osmosis, forming urine. The urine passes through the intestine, and into the rectum. There, nutrients diffuse back into the hemolymph.
The concentrated waste is then excreted. They are usually found in pairs and the number of tubules varies with the species of insect. Malpighian tubules are convoluted, which increases their surface area, and they are lined with microvilli for reabsorption and maintenance of osmotic balance. Malpighian tubules work cooperatively with specialized glands in the wall of the rectum.
Body fluids are not filtered as in the case of nephridia; urine is produced by tubular secretion mechanisms by the cells lining the Malpighian tubules that are bathed in hemolymph a mixture of blood and interstitial fluid that is found in insects and other arthropods as well as most mollusks.
Metabolic wastes like uric acid freely diffuse into the tubules. The secretion of ions alters the osmotic pressure which draws water, electrolytes, and nitrogenous waste uric acid into the tubules. Water and electrolytes are reabsorbed when these organisms are faced with low-water environments, and uric acid is excreted as a thick paste or powder. Not dissolving wastes in water helps these organisms to conserve water; this is especially important for life in dry environments.
Watch this video to see a dissected cockroach , including a close-up look at its Malpighian tubules. Improve this page Learn More. The many chetae of polychaetes are also arranged within fleshy, flat, paired appendages that protrude from each segment called parapodia , which may be specialized for different functions in the polychates.
The subclass Hirudinea includes leeches such as Hirudo medicinalis and Hemiclepsis marginata. The class Oligochaeta includes the subclass Hirudinia and the subclass Brachiobdella.
A significant difference between leeches and other annelids is the development of suckers at the anterior and posterior ends and a lack of chaetae. Additionally, the segmentation of the body wall may not correspond to the internal segmentation of the coelomic cavity. This adaptation possibly helps the leeches to elongate when they ingest copious quantities of blood from host vertebrates.
The subclass Brachiobdella includes species like Branchiobdella balcanica sketi and Branchiobdella astaci , worms that show similarity with leeches as well as oligochaetes. Figure 3. The a earthworm, b leech, and c featherduster are all annelids. Phylum Annelida includes vermiform, segmented animals. Segmentation is seen in internal anatomy as well, which is called metamerism. Annelids are protostomes. These animals have well-developed neuronal and digestive systems.
Some species bear a specialized band of segments known as a clitellum.
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