Response of the Organism: Hyalella azteca
Chemosensory organs in many crustaceans including Hyalella azteca allow them to locate food and mates while entirely avoiding predators. When detecting environmental changes such as the change in chemicals such as salinity, many amphipods have tiny hair-like organs containing sensory cells called sensilla (Hallberg, 2011). These chemosensory olfactory receptors are virtually found on many parts of the crustacean body including antennae, mouthparts and tips of the walking appendages (Hallberg, 2011).
In order to transfer and translate the sensory information, Hyalella azteca contain a thick nerve cord which is located near the ventral side of the body frame. Initially developed from stem cells, the nerve cord is the primary organ for all bodily functions such as digestion and even balance (Fabritius-Vilpoux et al, 2008). Since the body of Hyalella azteca is evenly segmented, ganglion which are nerve cell bodies receive sensory and movement information from the receptor cells located around the body (Victoria Museum 2009). When this information is fully transmitted it is processed on the spot, enabling rapid response (Victoria Museum 2009). This explains the immediate and swift turns performed by our organism when placed in a new environment. The alteration of salinity concentrations triggers a brief behavioral change in Hyalella azteca. As the amount of NaCl in the environment increases, the organism is predicted to move at a much slower rate or even experience brief agitation (Hallberg 2011). This can be due to the impaired vision from the dissolved salt particles. These series of behavior is quite crucial to survival because a change in surroundings can easily alter the proper ionic composition of bodily fluids, which are very sensitive to Hyalella azteca (Hallberg 2011). Fabritius-Vilpoux et al 2008. Engrailed-like immunoreactivity in the embryonic ventral nerve cord of the Marbled Crayfish, 8(4): 177-192....
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