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You are here:   animal list > Cryptoplax larvaeformis




Cryptoplax larvaeformis (Burrow, 1815)

Flexible Chiton of the Great Barrier Reef

Samantha Oliver (2011)




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The majority of marine molluscs, including Chitons, are herbivores (Little 1989). Cryptoplax larvaeformis is a known herbivore, adapted to a life in holes and crevices, and therefore taking on a wormlike body shape (technically known as vermiform) (Schwabe 2010). Chitons have been known to occupy a "homesite"  although this is yet to be formally studied in Cryptoplax larvaeformis. Chitons being a cautious creature are known to travel the same tracks and will never roam to far away from home (Kaas & Van Belle 1893). Some species of Chitons may not return to a scar (an impression created in the rock) but rather a specific home range (Little 1989), further studies are needed to identify thee habits in Cryptoplax larvaeformis. It is seen that Cryptoplax larvaeformis, like most other marine herbivores feed at night (Little 1989), it is unknown however whether their feeding is being driven by and/or cued by day/night cycles or an endogenous rhythm (driven by an internal, self-sustaining biological clock). A study conducted on Heron Island, Australia began to look at what the Chiton Cryptoplax larvaeformis used for it'd feeding cue, whether is uses a day/night cycle as a visual cue, or an endogenous rhythm.

The experiment:

Samples of Cryptoplax larvaeformis were collected at low tide from the reef crest at Shark bay on Heron Island, Australia. A total of 9 Cryptoplax larvaeformis were collected and transferred in holding tanks at The University of Queensland Research Station. The location of each indervidual was recorded and marked via flags and cable ties. 3 Cryptoplax larvaeformis were placed in tanks kept under normal day/night light conditions, outside. Another 3 Cryptoplax larvaeformis were kept in tanks that were kept under 24 hours dark conditions, and another 3 kept under 24 hour light conditions. Inside each of the 9 tanks was a shelter the Chitons could use. Each tank was left for a 24 hours period  to allow for acclimation of the new conditions. Observations on whether the animal was "in" or "out" of it's shelter were taken every 3 hours, over a 24 hours period. Upon completion of the data collection the individuals were taken back the their original location and released on the low tide.

Figure 1: Heron Island sample site, adapted from a picture taken by Nickj, sourced from Wikimedia Commons.


In all 3 light conditions it was seen that there was loose pattern of the Cryptoplax larvaeformis being out of their shelter in the night time measurements and were seen hiding in the day time measurements. (although, this was deemed insignificant due to come of the tanks not displaying this pattern). Across the treatments there was no significant differences in their behavior suggesting light was not a factor in the movement patterns in and out of their shelter.

So what does this mean?

It appears from the results of the study conducted Cryptoplax larvaeformis may be using an endogenous rhythem in orfer to time is roaming and /or it's feeding, however due to the lack of significance in these results further studies will need to be conducted to validate these conclusions. Cryptoplax larvaeformis is a highly crypic animal, hiding deep with living and dead coral (Schwabe 2010, Austin et al 1980), while they have aesthetes, their habitat suggests complete darkness, resulting in the thinking that aesthetes are not involved with feeding cues, as these cues never occur. These thoughts however, rely on the assumption that Cryptoplax larvaeformis is a homing species of Chiton. It was found in a past study conducted by Lewis (1954) that in a population of limpets only 85% of the individuals homes, and in another population only 15% homed. It was also seen in Lewis's study that these differences in homing behaviors coincided with differences in habitats. If Cryptoplax larvaeformis is seen to not be a homing species it suggests they move about their habitat as a whole, suggesting aesthetes do play a role in feeding cues. One important factor emphasis in past studies is that, while endogenous rhythms may be present, they are never present in isolation. Endogenous rhythms can be modified in relation to day/night cycles. Habitat was also found to be key in endogenous rhythms, with a study conducted by Horn (1986) finding that the species of Chiton Pelliscrpentis was active at night on the high shore but was active in the day and the night on the low shore. These differences in behavior found by Horn could be related to the predation rick present in the two habitats, which becomes another factor in foraging behaviors. On the high shore there may be a higher predation risk leading to the nocturnal behavior displayed by the species pelliscrpentis, and a comparatively lower predation risk seen in the low shore, meaning the Chitons can spend the day and night feeding. The study conducted on Heron Island considered little to none of these factors, and further field research needs to be conducted to get information on behavior in the natural habitat and natural behaviors. This information is vital to produce significant results in manipulative, laboratory studies.