Rhinophore
Encyclopedia
A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea slugs, marine
gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.
from ancient greek
ῥίς rhis and from its genitive ῥινός rhinos. "Phore" means "to bear" from New Latin
-phorus and from Greek -phoros (φορος) "bearing", a derivative of phérein (φέρειν).
receptors, also known as chemosensor
y organs.
Rhinophores are specialized anterior sensory organs on the dorsal surface of the head. Rhinophore are retractile and primarily used for distance chemoreception and rheoreception (response to water current).
The "scents" detected by rhinophores are chemicals dissolved in the sea water. The fine structure of the rhinophore provides a large surface area so that chemical detection is maximized. This allows the nudibranchs to stay close to their food source (for example species of sea sponges) which are also the living substrate they preferentially inhabit.
In the sea hare Aplysia californica, the rhinophores are able to detect pheromone
s.
The neuroanatomical organization of rhinophores includes a rhinophore groove where most of the sensory cells appear to be concentrated. Its sensory epithelium
contains sensory neuron
s that project axon
s back to rhinophore ganglia and dendrite
s that end in either a surface-exposed cilium or a small protuberance.
s: the oral tentacles, which are found more ventrally, are possibly involved in contact chemoreception and mechanoreception in Aplysia californica.
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.
Etymology
The name relates to the rhinophore's function as an organ of "smell". "Rhino-" means noseNose
Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration in conjunction with the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes through the pharynx, shared with the...
from ancient greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
ῥίς rhis and from its genitive ῥινός rhinos. "Phore" means "to bear" from New Latin
New Latin
The term New Latin, or Neo-Latin, is used to describe the Latin language used in original works created between c. 1500 and c. 1900. Among other uses, Latin during this period was employed in scholarly and scientific publications...
-phorus and from Greek -phoros (φορος) "bearing", a derivative of phérein (φέρειν).
Function
Rhinophores are scent or tasteTaste
Taste is one of the traditional five senses. It refers to the ability to detect the flavor of substances such as food, certain minerals, and poisons, etc....
receptors, also known as chemosensor
Chemosensor
A chemoreceptor, also known as chemosensor, is a sensory receptor that transduces a chemical signal into an action potential. In more general terms, a chemosensor detects certain chemical stimuli in the environment.- Classes :...
y organs.
Rhinophores are specialized anterior sensory organs on the dorsal surface of the head. Rhinophore are retractile and primarily used for distance chemoreception and rheoreception (response to water current).
The "scents" detected by rhinophores are chemicals dissolved in the sea water. The fine structure of the rhinophore provides a large surface area so that chemical detection is maximized. This allows the nudibranchs to stay close to their food source (for example species of sea sponges) which are also the living substrate they preferentially inhabit.
In the sea hare Aplysia californica, the rhinophores are able to detect pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
s.
Protection
To protect the prominent rhinophores against nibbling by predators including fish, most species of dorid nudibranchs are able to withdraw their rhinophores into a pocket beneath the skin.Structure
Rhinophores are small. For example in reproductively mature Aplysia adults the rhinophore is about 1 cm in length.The neuroanatomical organization of rhinophores includes a rhinophore groove where most of the sensory cells appear to be concentrated. Its sensory epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
contains sensory neuron
Sensory neuron
Sensory neurons are typically classified as the neurons responsible for converting external stimuli from the environment into internal stimuli. They are activated by sensory input , and send projections into the central nervous system that convey sensory information to the brain or spinal cord...
s that project axon
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
s back to rhinophore ganglia and dendrite
Dendrite
Dendrites are the branched projections of a neuron that act to conduct the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project...
s that end in either a surface-exposed cilium or a small protuberance.
See also
Comparison with oral tentacleTentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s: the oral tentacles, which are found more ventrally, are possibly involved in contact chemoreception and mechanoreception in Aplysia californica.
Further reading
- Wertz A., Rössler W., Obermayer M. & Bickmeyer U. (6 April 2006) "Functional neuroanatomy of the rhinophore of Aplysia punctata". Frontiers in ZoologyFrontiers in ZoologyFrontiers in Zoology is a peer-reviewed online scientific journal in the field of "all aspects of animal life". In 1999 it was the first open access journal focussing on zoology. It is published online only...
3: 6.