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The nervous system consists of two ventral nerve cords, which are usually fused into a single structure, and three or four pairs of smaller nerves per body segment. Only a few aquatic oligochaetes have eyes, and even then they are only simply ocelli. Nonetheless, their skin has several individual photoreceptors, allowing the worm to sense the ...
Like the vertebrate spinal cord, the function of the ventral nerve cord is to integrate and transmit nerve signals. It contains ascending and descending neurons that relay information to and from the brain, motor neurons that project into the body and synapse onto muscles, axons from sensory neurons that receive information from the body and environment, and interneurons that coordinate ...
The sympathetic nervous system consists of nerve plexuses in the epidermis and alimentary canal. (A plexus is a web of connected nerve cells.) The nerves that run along the body wall pass between the outer circular and inner longitudinal muscle layers of the wall. They give off branches that form the intermuscular plexus and the subepidermal ...
However, 'earthworm' can be a source of confusion since, in most of the world, other species are more typical. For example, through much of the unirrigated temperate areas of the world, the "common earthworm" is actually Aporrectodea (=Allolobophora) trapezoides, which in those areas is a similar size and dark colour to L. terrestris.
Siboglinidae is a family of polychaete annelid worms whose members made up the former phyla Pogonophora and Vestimentifera (the giant tube worms). [1] [2] The family is composed of around 100 species of vermiform creatures which live in thin tubes buried in sediment (Pogonophora) or in tubes attached to hard substratum (Vestimentifera) at ocean depths ranging from 100 to 10,000 m (300 to ...
The following are two lists of animals ordered by the size of their nervous system.The first list shows number of neurons in their entire nervous system. The second list shows the number of neurons in the structure that has been found to be representative of animal intelligence. [1]
The enteric nervous system functions to control the gastrointestinal system. Nerves that exit from the brain are called cranial nerves while those exiting from the spinal cord are called spinal nerves. The nervous system consists of nervous tissue which, at a cellular level, is defined by the presence of a special type of cell, called the ...
Pheretima is a genus of earthworms found mostly in New Guinea and parts of Southeast Asia.. Species belonging to the genus Pheretima have a clitellum, which is a band of glandular tissue present on segments 14 to 16.