CHEMORECEPTION IN MARINE SHRIMP
By: C.arlos A. Ching (cchingm@alicorp.com.pe)
Nicovita-ALICORP SAA Technical Service
Introduction
Chemoreception is the process by which organisms respond to chemical stimuli. The
process starts when a chemical stimulus gets in contact with chemoreceptors (specialized
cells that transform the immediate effect of such substances into nervous impulses). The
nervous cell (neuron) that translates the chemical stimulus into an impulse is called the
“Primary Receptor”, while the cell which is not a neuron but responds to the stimulus by
induction to the adjacent nervous cell is called the “Secondary Receptor”.
Shrimp chemoreceptors
In marine shrimp, reactions to dietary chemicals and other substances have been found in
different bodily regions containing chemoreceptors, which can be of two types: “Distance
Chemoreceptors” found in the antennas and antennules, which not only allow shrimp to
detect food residues buried in the sediment, but also work in the processes of both mating
and detection of danger as a predator approaches. On the other side, “Contact
Chemoreceptors” located in the periopods and buccal parts play active roles in the feeding
process (Carr & Gurin, 1975.)
In marine shrimp the sight sense is very poor. Therefore, the animal needs to recognize its
environment by the tactile, gustatory (taste) and olphactory (smell) senses. Tactile
chemoreceptors are typically found in the antennas. On the other hand, the inner hairs in
periopod chela, maxillipeds, and buccal parts are the gustatory chemoreceptors. Lastly, the
olphactory sense is governed by chemoreceptors in the antennules and some parts of the
antennas. (Nunes, 2006). Some sites in shrimp appendices are more sensitive than others
(Figure 1.)
Shrimp chemoreceptors are closely linked to artificial feed attractability and palatability.
These chemoreceptors can distinguish among many chemical types, allowing shrimp to
discriminate edible from rejectable materials, and also determine the time that the animal
will spend nearby the feed. The tactile sense located in the antennas allow shrimp for
distinguishing hard from soft feeds. Likewise, chemoreceptors in the maxillipeds and other
buccal parts work as a palate so that shrimp can accept or reject the passage of feed into its
digestive system (a function known as palatability).
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Antennule
Antenna
Chela
Maxillipeds
Buccal Parts
Chemoreceptors:
High
Moderate
Low
Figure 1. Map showing the chemosensorial ability in the appendices of Litopenaeus
vannamei (Reference: Nunes, 2006)
Feed attractants for shrimp
Attractants are water-soluble metabolites with low molecular weight, that are included in
the feed in an attempt to attract the shrimp thus promote feed intake. An interesting study
was undertaken Ceara´s Federal University, Brazil, using nine commercially-available feed
attractants, as described below:
1. VDB 80 (80% crude protein from dry plant biomass)
2. VDB 68 (68% crude protein from dry plant biomass, plus glutamate and betaine)
3. CAA (an amino acid complex including: alanine, valine, glycine, proline, serine,
histidine, glutamic acid, tyrosine y betaine)
4. CSFP (A fish soluble condensed protein)
5. SLM (Squid liver meal)
6. BET (Betaine)
7. DFSLH (Histamine-low fish dry solubles)
8. DFSHH (Histamine-high fish dry solubles)
9. WSPH (Whole squid protein hydrolisate)
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Results showed that CFSP, CAA, SLM and WSPH had the highest numbers of positive
responses as attractants. In general, shrimp detected faster and spent more time eating the
amino acid complex (CAA) than any other ingredients (Nunes 2006). A positive correlation
was found between the % CFSP and increased attractability. A cadaverine/histamine
combination seems to promote attractability when mixed with some of the other
ingredients.
Conclusion
Marine shrimp have developed mechanisms to compensate for their poor visual sense, by
using chemoreceptors located in both locomotion appendices and buccal parts, as effective
tactile, gustatory and olphactory senses. Chemoreception plays an important role in the
processes of feeding, mating, and defense against predators.
On the other hand, studies have identified amino acid complexes and marine-origin
compounds as effective attractants that can be included in the feed of farmed marine
shrimp.
References
Carr, W. E. and S. Gurin 1975. Chemoreception in the Shrimp, Palaemonetes pugio:
Comparative study of stimulatory substances in Human Serum. Biol. Bull., 148:380392.
Nunes, A.J.P. 2006. An update on the use of Chemo attractants in shrimp feeds. Aquaexpo
2006 – Guayaquil, Ecuador.
Nunes, A.J.P., M.V.C. Sá, F.F. Andriola-Neto, G. Oliveira & D. Lemos, 2006. Measure of
feeding stimulation of Commercial attractants for white shrimp Litopenaeus
vannamei through behavioral bioassays and Ingredient chemical profile. Abstracts
WAS Aqua 2006 (Florence, Italy).
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