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You are here:   OldClasses > 2012 > Echinaster luzonicus | Ellen Jackson

 

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Echinaster luzonicus
(Gray, 1840)

Luzon Seastar



Ellen Jackson (2012)
 

 

Fact Sheet

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Summary


Physical Description


Ecology


Life History & Behaviour


Anatomy & Physiology


Evolution & Systematics


Biogeographic Distribution


Conservation & Threats


References & Links

Anatomy & Physiology

Through a dissection of one E. luzonicus ray it was evident that the ray contains a radial canal (Figure 3) which is where the ampulla is connected. The radial canal is made of calcium carbonate and is the ‘back bone’ of the sea star. The ampulla is the top of the tube foot (Figure 1) and connects it to the water vascular system (see Life History section). In figure 1 the tube foot is extended at full reach showing the full extension in comparison to figure 2 where the tube foot is pulled into the ambulacral groove. At the end of the tube foot there is a sucker for E. luzonicus to attach to substrata.



Figure 1


Figure 2


The pyloric colon (Figure 3) is the extension of the stomach. At the base of the ray near the central disc you would normally find the gonads however in this specimen they were not evident. The gonads are placed in the ray as E. luzonicus is seen to undergo asexual reproduction through autotomy, the loss of a ray can regenerate into a new organism. The gonads in the ray further allow the new organism to reproduce.




Figure 3


On the end of the rays are light sensitive tube feet that are thinner and smaller than the rest of the feet (Figure 4).  These tube feet surround the ocelli (‘eye’) of E. luzonicus (Figure 5). They have an ‘eye’ on each ray. This ability to detect light is due to photoreceptor pigments (Oviatt 1969; Ullrich-Lüter 2011; Figure 5). However studies have shown that after removal of these pigments the sea star is still able to respond to light stimuli, that has been attributed to skin photoreceptors (Rockstein 1956). This also corresponds to the observations seen at Heron Island (see Physical Description) as the E. luzonicus collected and observed changed colour potentially responding to light stimuli. 




Figure 4





Figure 5




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