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Nephridiopores are present in ventral region. The nephridium consists of an opening called the nephrostome , a long convoluted tubule , and another opening called the nephridiopore. Body fluids are filtered in through the nephrostome and passed through the convoluted tubule system. [ 3 ]
The nephridium (pl.: nephridia) is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidneys (which originated from the chordate nephridia).
The sperm are formed into little balls called spermatophores by specialist organs. When dispersed, they become amoeboid and make their way through the body wall of an adult worm before fertilising eggs in the metacoel. The resulting zygotes make their way out through the nephridiopores and become planktonic larvae. [4]
Sperm exit by the nephridiopores and some are captured by the lophophores of individuals of the same species. Species that lay small fertilized eggs release them into the water as plankton, [1] while species with larger eggs brood them either in the body's tube or stuck in the center of the lophophore by adhesive. [13]
The function of these cells is to regulate the osmotic pressure of the worm, and maintain its ionic balance. Microvilli in the tube cell may be used to reabsorb some ions. [1] Molecules enter the tubule in tube cells through the gap between the flame cell and tube cell for excretion. [2]
Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of about 1300 known species. [ 2 ] [ 3 ] Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies.
The spoon worm is preyed on by bottom feeding fish such as flounders, Dover sole (Microstomus pacificus) and bat rays (Myliobatis californicus). [ 3 ] In the 1970s, Listriolobus pelodes was found near wastewater discharge outlets off Los Angeles at densities of up to 1,500 individuals per square metre (11 square feet). [ 5 ]
Thus each worm becomes the genetic father of some of their offspring (due to its own sperm transferred to other earthworm) and the genetic mother (offsprings from its own egg cells) of the rest. As the worm slips out of the ring, the ends of the cocoon seal to form a vaguely onion-shaped incubator in which the embryonic worms develop. Hence ...