Recruitment to the reef
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Asexual reproduction

 
Asexual reproduction of sea stars is considered in this section. Click on an icon to learn about asexual reproduction in another reef organism. hot buttons for asexal reproduction section of BCCR website hot-button icon for linking to the topic of asexual reproduction in seaweeds in BCCR website hot-button icon for linking to the topic of asexual reproduction in sponges in BCCR website hot-button icon for linking to the topic of asexual reproduction in gorgonians in BCCR website hot-button icon for linking to the topic of asexual reproduction in corals/zoanthids in BCCR website hot-button icon for linking to the topic of asexual reproduction in seastars in BCCR website hot-button icon for linking to the topic of asexual reproduction in tunicates in BCCR website
 
 
seahorse dive leader for BIOLOGY OF CARIBBEAN CORAL REEFS website photograph of a cushion star taken from a video

Unlike other echinoderms such as sea urchins, sea cucumbers, and crinoids, sea stars are not common on Caribbean reefs. Moreover, the species featured here, the cushion star, does not reproduce asexually. However, the comet-star species featured below does, and the mode it uses is quite interesting - Turks & Caicos, 2003, Cozumel, 2005

NOTE Oreaster reticulatus

NOTE Linckia guildingii

 
 

Asexual reproduction: sea stars

 

photograph of comet star Linckia guildingii
Comet sea stars Linckia sp. have an unusual method of asexual reproduction. An individual will autotomise 4 of its arms. Later, each separate arm and the original central disc sprout the required number of new arms to make more sea stars. The central disc portion of the adult carries the mouth, digestive stomachs, and anus. Of course, each offspring is a genetic clone of the original. The order of events involved is a bit more complicated than described here, as shown in the sequence below.

NOTE "autotomy": self-induced loss of a body part

Post-autotomy comet star Linckia guildingii. The arms autotomise through dissolution of
connective tissue binding them to the body followed by contraction of special muscles

 
photograph 1 in series of 6 showing regeneration sequence in sea star Linckia photograph 2 in series of 6 showing regeneration sequence in sea star Linckia photograph 3 in series of 6 showing regeneration sequence in sea star Linckia
Series showing asexual reproduction in Linckia Four arms are autotomised from the central disc One arm remains attached to the central disc
photograph 4 in series of 6 showing regeneration sequence in sea star Linckia photograph 5 in series of 6 showing regeneration sequence in sea star Linckia photograph 6 in series of 6 showing regeneration sequence in sea star Linckia
Each of the 4 autotomised arms now sprouts 5 new arms. However, note that the central disc grows only 4 arms Each autotomised arm drops a single arm to make a 5-armed individual. No arm is dropped from the central disc The offspring feed and their arms grow to requisite length, as does the arm attached to the central disc
   
 

So, the total yield of offspring from a single individual is 4. The strategy seems odd, as 5 dropped arms would seem to be more logical, but its selective value may be in the retention of at least some motility for the central disc while it regenerates the missing 4 arms. Note that retention of the mouth for feeding is not an issue, for the other 4 dropped arms are able to regenerate from nutrients and energy materials stored in the hepatic caeca in the arms, without the requirement for feeding.

Note that survival of the "youngsters" is virtually assured, but recruitment potential is clearly limited.

 
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