Predators may play an important role in affecting the fitness of preys. Many organisms have thus evolved strategies to prevent predation. Recognition of predator presence may be achieved by vision, olfaction, tactile sense or detection of water motion. Some organisms sense predators directly; others associate the injuries of victims to the presence of predators. There are many brittlestars (Ophiocoma scolopendrina) at the intertidal zone of Kenting, southern Taiwan and they suffer high frequencies of injuries in the wilds. Since their predators are likely to be diverse, we want to know if O. scolopendrina has the ability to sense the presence of predators, indirectly. We have two hypotheses: firstly, the avoidance behavior is elicited specifically in response to predators, secondly, the avoidance behavior is a general response to unfamiliar elements in the water mass. Our experiments revealed that the tested individuals would avoid conspecific viscera liquids and also that of other echinoderms¡¦. They are more likely to respond to conspecific viscera liquids. And O. scolopendrina hardly respond to solutions prepared from other organisms, e.g., fish, pork, macroalgae, freshwater. This behavior may help brittlestars reduce the probability of encountering predators. The results are compatible with the first hypothesis only. The effect of tide was also explored by testing in different times, but the frequencies of avoidance responses were independent of the tide. Furthermore, the subtidal species Ophiocoma dentata was also tested for the behavior. They escaped from conspecific viscera liquid as well as that of O. scolopendrina. This species, however, could not distinguish the liquids from the two brittlestar species. In conclusion, the avoidance behaviors of the ophiocomid brittlestars are adaptations for avoiding predators, not for avoiding unfamiliar environments.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0817110-122459 |
| Date | 17 August 2010 |
| Creators | Hsu, Chia-ling |
| Contributors | Ker-yea Soong, Shyh-min Chao, Jin-Hua Cheng |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0817110-122459 |
| Rights | unrestricted, Copyright information available at source archive |
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