The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals—that is, all multicellular animals except sponges and jellyfish. It is a structure composed of nervous tissue positioned along the rostral to caudal axis of the body and may have an enlarged section at the rostral end which is a brain. Not all animals with a central nervous system have a brain, although the large majority do.
The basal ganglia are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an external and internal region, and in the division of the striatum. The basal ganglia are situated at the base of the forebrain and top of the midbrain. Basal ganglia are strongly interconnected with the cerebral cortex, thalamus, and brainstem, as well as several other brain areas. The basal ganglia are associated with a variety of functions, including control of voluntary motor movements, procedural learning, habit learning, conditional learning, eye movements, cognition, and emotion.
The gastropods, commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda.
The sympathetic nervous system (SNS) is one of two divisions of the autonomic nervous system, along with the parasympathetic nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.
Scallop is a common name that is primarily applied to any one of numerous species of saltwater clams or marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families within the superfamily Pectinoidea, which also includes the thorny oysters.
The cerebrum, telencephalon or endbrain, is the largest part of the brain containing the cerebral cortex, as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In the human brain, the cerebrum is the uppermost region of the central nervous system. The cerebrum develops prenatally from the forebrain (prosencephalon). In mammals, the dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. The cerebrum is also divided into approximately symmetric left and right cerebral hemispheres.
Athetosis is a symptom characterized by slow, involuntary, convoluted, writhing movements of the fingers, hands, toes, and feet and in some cases, arms, legs, neck and tongue. Movements typical of athetosis are sometimes called athetoid movements. Lesions to the brain are most often the direct cause of the symptoms, particularly to the corpus striatum. This symptom does not occur alone and is often accompanied by the symptoms of cerebral palsy, as it is often a result of this physical disability. Treatments for athetosis are not very effective, and in most cases are simply aimed at managing the uncontrollable movement, rather than the cause itself.
Cephalization is an evolutionary trend in which, over many generations, the mouth, sense organs, and nerve ganglia become concentrated at the front end of an animal, producing a head region. This is associated with movement and bilateral symmetry, such that the animal has a definite head end. This led to the formation of a highly sophisticated brain in three groups of animals, namely the arthropods, cephalopod molluscs, and vertebrates.
The tusk shells or tooth shells, technically the Scaphopoda, are members of a class of shelled marine mollusc with worldwide distribution, and are the only class of exclusively infaunal marine molluscs. Shells of species within this class range from about 0.5 to 15 cm in length. Members of the order Dentaliida tend to be significantly larger than those of the order Gadilida.
Limpets are a group of aquatic snails that exhibit a conical shell shape (patelliform) and a strong, muscular foot. Limpets are members of the class Gastropoda, but are polyphyletic, meaning the various groups called "limpets" descended independently from different ancestral gastropods. This general category of conical shell is known as "patelliform" (dish-shaped). All members of the large and ancient marine clade Patellogastropoda are limpets. Within that clade, the members of the Patellidae family in particular are often referred to as "true limpets".
The Patellogastropoda, common name true limpets and historically called the Docoglossa, are members of a major phylogenetic group of marine gastropods, treated by experts either as a clade or as a taxonomic order.
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda. The members are known as molluscs or mollusks. Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied.
The nervous system of gastropods consists of a series of paired ganglia connected by major nerve cords, and a number of smaller branching nerves. It is sometimes called ganglionic.
Pseudunela cornuta is a species of minute sea slug, an acochlidian, a shell-less marine and temporarily brackish gastropod mollusk in the family Pseudunelidae. Adults are about 3 mm long and live in the spaces between sand grains.
Bathyacmaea secunda is a species of very small, deep-sea limpet, a marine gastropod mollusk in the family Pectinodontidae. This species inhabits the dark, chemosynthesis-based marine communities of ocean vents and cold seeps near Japan.
The term epiathroid is used to describe the arrangement of ganglia in the nervous system of molluscs. In the epiathroid state, the pleural ganglia of the "chest" and the pedal ganglia of the "feet" lie close to the cerebral ganglia of the "head" forming a neural cluster which begins to approximate a brain. It is a condition characteristic of the Mesogastropoda and Neogastropoda, and is the obverse of the more-primitive hypoathroid condition in which the pleural and pedal ganglia lie close together under the animal's gut and communicate with the cerebral ganglia via long connectives. The Archaeogastropoda clade is described as "hypoathroid", and is the clade closest to the original hypothetical ancestral mollusc. In between these two extremes lie those animals with a dystenoid nervous system in which the pleural and cerebral ganglia are closer than they are in the hypoathroid condition but still further apart than they are in the epiathroid one.
Berghia stephanieae is a species of sea slug, an aeolid nudibranch. It is a marine gastropod mollusc in the family Aeolidiidae. It was previously known as Aeolidiella stephanieae.
A dystenoid nervous system is an arrangement of ganglia in the anterior region of some molluscs in which the cerebral and pleural ganglia are situated closer to each other than they are in those molluscs with the more archaic hypoathroid nervous system but still farther apart than those animals with an evolutionarily more recent epiathroid nervous system.
A circumesophageal or circumpharyngeal nerve ring is an arrangement of nerve ganglia around the esophagus/ pharynx of an animal. It is a common feature of nematodes, molluscs, and many other invertebrate animals, though it is absent in all vertebrate animals and is not structurally possible in simpler ones such as water bears.
Bathyhedyle boucheti is a species of panpulmonate slug, a deep-sea dwelling gastropod native to the continental slope off the coast of Mozambique. It is the first ever such panpulmonate slug to be discovered at such depths. It is the only known member of its family group. Its radular formula is 1.1.2.
