What is Baroreceptors chemoreceptors and statocyst
Baroreceptors:
Baroreceptors
(Baro=weight + receptor) sense changes in pressure. Responses to pressure changes
have been identified in ocean dwelling copepod crustaceans, ctenophore, jelly
fish medusae and squids. Some intertidal crustaceans coordinate migratory
activity with daily tidal movement possibly in response to pressure changes
accompanying water depth changes.
Chemoreceptors:
Chemo=pertaining
to chemistry. They respond to chemicals. Protozoa have a chemical sense. They
respond with avoidance behaviour to acid, alkali and salt stimuli. Specific
chemical attract predatory ciliates to their prey. Chemoreceptors of many aquatic
invertebrates are located in pits or depressions through which water carrying
the specific chemicals may be circulated. In Arthropods chemoreceptors are
usually on the antennae, mouth parts and legs in the form of hollow hairs
containing chemo sensory neurons. The types of chemicals which invertebrates
respond are closely associated with their life styles e.g. humidity detection,
pH assessment, prey tracking, food recognition and mate location. The antennae
of male silk worm (Bombyx mori) can detect one mbobykol molecule in over trillion
molecules of air. Female silk moths secrete bombykol as a sex attractant which
enables a male to find female at might from several miles down wind, an ability
that confers obvious reproductive advantage in a widely disappeared species.
Statocysts:
Statocysts are
found in various gastropods, cephalopds, crustaceans, nemertines, polychaetes
and sayphozoans. These animals use information from statocysts in different
ways. For example burrowing invertebrates cannot rely on photoreceptors for
orientation instead, they rely on georeceptors for orientation within the
substation. Most georeceptors are statocysts (statos=standing +
kystis=Bladder). Statocysts consist of a fluid filled chamber lined with cilia
bearing sensory epithelium, within the chamber is a solid granule called a
statolith (lithos=stone). Any movement of the animal changes the position of
the statolith and moves the fluid, thus altering the intensity and pattern of
information arising from the sensory epithelium.
For example when
an animal moves both the movement of the statolith and the flow of fluid over
the sensory epithelium provide information about animals linear and rotational
acceleration relative to the environment.
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