Search results
Results From The WOW.Com Content Network
The alimentary canal consists of a mouth, buccal cavity (generally running through the first one or two segments of the earthworm), pharynx (running generally about four segments in length), esophagus, crop, gizzard (usually), and intestine. [28] Food enters at the mouth. The pharynx acts as a suction pump; its muscular walls draw in food.
The digestive tract is essentially a tube running the length of the body, but has a powerful muscular pharynx immediately behind the mouth cavity. In many species, the pharynx simply helps the worm suck in food, but in many aquatic species, it can be turned inside out and placed over food like a suction cup before being pulled back in.
Earthworms store their partners' sperm in spermathecae ("sperm stores") and then the clitellum produces a cocoon that collects ova from the ovaries and then sperm from the spermathecae. Fertilization and development of earthworm eggs takes place in the cocoon. Leeches' eggs are fertilized in the ovaries, and then transferred to the cocoon.
Invertebrates also have a pharynx. Invertebrates with a pharynx include the tardigrades, [12] annelids and arthropods, [13] and the priapulids (which have an eversible pharynx). [14] The "pharynx" of the nematode worm is a muscular food pump in the head, triangular in cross-section, that grinds food and transports it directly to the intestines ...
Some species break up and soften food first by secreting enzymes in the gut or pharynx (throat). [5] All animals need to keep the concentration of dissolved substances in their body fluids at a fairly constant level. Internal parasites and free-living marine animals live in environments with high concentrations of dissolved material, and ...
In general, however, they possess a pair of jaws and a pharynx that can be rapidly everted, allowing the worms to grab food and pull it into their mouths. In some species, the pharynx is modified into a lengthy proboscis. The digestive tract is a simple tube, usually with a stomach part way along.
The pharynx is an extensible tube-like organ bearing a complex muscular coat. It specializes as a penetration organ for those planarians that feed on arthropods; or as a grasping organ for those planarians that feed on other soft bodied invertebrates such as earthworms.
The genus Lumbricus contains some of the most commonly seen earthworms in Europe among its nearly 700 valid species. [2] Characteristics of some commonly encountered species are: Lumbricus rubellus is usually reddish brown or reddish violet, iridescent dorsally, and pale yellow ventrally. They are usually about 25–105 mm in length, and have ...