Select the search type
 
  • Site
  • Web
Search
You are here:   OldClasses > 2012 > Echinaster luzonicus | Ellen Jackson

 

Minimize

 


Echinaster luzonicus
(Gray, 1840)

Luzon Seastar



Ellen Jackson (2012)
 

 

Fact Sheet

Minimize

Summary


Physical Description


Ecology


Life History & Behaviour


Anatomy & Physiology


Evolution & Systematics


Biogeographic Distribution


Conservation & Threats


References & Links

Life History & Behaviour


Feeding

E. luzonicus are omnivores with a mouth (Figure 1; Mah & Blake 2012) on the underside where the osphegous is small and leads to the phyloric stomach and then extends to the pyloric ceca (see Anatomy and Physiology). E. luzonicus is able to digest its food externally via everting the stomach (Ferguson 1969). Digestion is mainly by extracellular means and nutrient absorption occurs in the pyloric ceca (Ferguson 1969).


Figure 1



Respiration

Respiration occurs through the tube feet and papulae (on the upperside, Figure 2). Papulae supply oxygen to the coelom, the gut, gonads,muscles and rays.

Figure 2

Locomotion

Water vascular system

The water vascular system (WVS) consists of the tube feet which end at the ampulla that sits in the radial canal (see Anatomy and Physiology)(McCurley 1995). The radial canal extends to the madreporic ampulla which joins the madreporite. The madreporite is a ‘valve’ of pores that filters sea water into the WVS (McCurley 1995). The WVS allows movement, respiration and feeding manipulation.


Figure 3

Figure 4


Tube feet are extendable with suckers on the end to allow attachment to substrate or prey. On the end of the rays are light sensitive tube feet (Figure 5). These feet are first to come out of the ambulacral groove (Figure 1) to determine if the area is ‘safe’. In urchin studies it has been seen that the spines move in relation to shadows (Ullrich-Lüter 2011). Please see anatomy and physiology for more information on the light sensitive tube feet.  



Figure 5



Reproduction

E. luzonicus can reproduce sexually or asexually. Sexual reproduction in this species is via lecithotrophic development. Lecithotrophic development is where an egg has large reserves of yolk allowing the larvae nutrients, this means that when in the plankton stage the larvae does not have to feed (McEdward 2001). The larvae are called a brachiolaria that has specialised rays for attachment to the substrate (McEdward 2001). Once attached the brachiolaria larvae undergoes metamorphosis to become a young E. luzonicus (McEdward 2001).

Asexual reproduction within E. luzonicus is by autotomy where a ray can be dropped off and will become a separate, fully functioning E. luzonicus (Charonia Research 1985; Figure 7). They develop a ‘comet’ ray (Figure 6) that can drop off and regenerate however to reach adult stage it may take 2-3years (McAlary 1993). On the main body the ray is able to regenerate (Figure 7).

    
Figure 6 Figure 7

On one specimen found at Heron Island at A/B point a smaller E. luzonicus was found attached upside down on a larger E. luzonicus (Figure 8).This has never been reported before and may be another form of asexually reproduction or an anomaly. 


Figure 8



Images

Minimize

(0 objects)

Album: This is a private album that is not visible to anonymous users All albums

Summary:

Date:

Insufficient permission
You are are not authorized to view the requested album. Contact your administrator to request access.

There are no objects in this album.

Classification

Minimize