Biology of Sensory Systems

Product Description:

Since publication of the first edition, huge developments have taken place in sensory biology research and new insights have been provided in particular by molecular biology. These show the similarities in the molecular architecture and in the physiology of sensory cells across species and across sensory modality and often indicate a common ancestry dating back over half a billion years.

Biology of Sensory Systems has thus been completely revised and takes a molecular, evolutionary and comparative approach, providing an overview of sensory systems in vertebrates, invertebrates and prokaryotes, with a strong focus on human senses.

Written by a renowned author with extensive teaching experience, the book covers, in six parts, the general features of sensory systems, the mechanosenses, the chemosenses, the senses which detect electromagnetic radiation, other sensory systems including pain, thermosensitivity and some of the minority senses and, finally, provides an outline and discussion of philosophical implications.

New in this edition:

• Greater emphasis on molecular biology and intracellular mechanisms
• New chapter on genomics and sensory systems
• Sections on TRP channels, synaptic transmission, evolution of nervous systems, arachnid mechanosensitive sensilla and photoreceptors, electroreception in the Monotremata, language and the FOXP2 gene, mirror neurons and the molecular biology of pain

• Updated passages on human olfaction and gustation.

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Copepoda Harpacticoida: Biology (Reproduction and post-embryonic development)

Harpacticoid copepods are gonochoristic and fertilization is by copulation involving the attachment of a spermatophore by the male to the copulatory pore of the female. Sperm are stored in the female seminal receptacle, the eggs are fertilized as they emerge into the genital antrum and are united by their outer membranes to form a single or double egg-sac. Brood size varies from about three (in many interstitial species) to over 100 (in some phytal species) with the norm in the range of 15-30 eggs per brood. The number of broods per single copulation varies from 2-15 (in laboratory cultured species) and some species prduce broods throughout the year (most common in phytal habitats) whilst others have a well defined breeding season. Harpacticoids have direct benthic development and pass throughout six naupliar stages followed by a six copepodite stages, copepodite VI being the adult.

Copepoda Harpacticoida: Biology (Feeding)

Potential food sources of harpacticoids are organic matter and detritus (or more probably the decomposer organisms, such as bacteria, associated with detritus), other small autotrophic and heterotrophic organisms such as microalgae and ciliates, dissolved organic matter and specialized energy sources such as mucus and other extracellular polymer secretions. Direct carnivory of metazoan organisms is relatively unknown amongst harpacticoids but utilisatin of any particular food source is difficult to deduce from the morphology of the feeding apparatus, except for filter feeding in Longipediidae and Canuellidae and mucus trap feeding in the Leptasticidae. Most other harpacticoids are regarded as surface feeders and it has been suggested that, amongst these, food resources may be portioned by adaptations for feeding on different types and shapes of surfaces: a) selective epistrate feeders; b) edge scrapers; c) plane-sweepers and sand-filers and d) solid feeders. In addition, some harpacticoids are known to be able to cultivate or concentrate suitable food organisms either by producing mucus which acts as a growth substrate for bacteria or through commensal associations with other organisms such as mollusks and Crustacea. A few harpacticoids have very specialized food sources, such as the medullary tissue of red algae utilized by frond-mining species in the Thalestridae.

Copepoda Harpacticoida: Biology (Ecology)

Harpacticoid copepods are essentially free-living organisms, although a few are planktonic (Microsetella, Euterpina, Clymnestra, Macrpsetella) or found in association with other organisms . In marine sedimente, they are usually the second most abundant meiofaunal taxon afternematodes but tend to become the dominant taxon in coarsed-grained sediments and on marine algae. Generally, there is a reduction in abundance with increasing depth of water. Harpacticoids can be found living in sediment particle interstices, burrowing in the sediments, or living on the sediment surface. Small, vermiform, interstit10al speciesnd broad, slightly flattened, epibenthic species dominate the sand sediments but the former disappear from community when silt/clay content of the sediment exceeds about 10%. In addition to species assemblages being associated with particular substrata, there is both horizontal and vertical zonation of species within the sediment. Harpacticoid is general are known to be intolerant of anaerobic conditions and are therefore confined to the oxygenated layers of the sediment, usually the top 1 cm in muddy sediments but as much as the top 50-100 cm on high energy sand beaches.