Starfish are not only very beautiful creatures but they’re also astounding in that some breeds can reproduce without the presence of a mate. These starfish reproduce either through the loss of an arm…which then generates a new centre disc and new arms…or through the splitting of the starfish in two, which results in the same growth of more arms and a complete disc.
Starfish which regenerate in this way are effectively asexual…though the resultant “new” starfish will share the same genetic profile as that of its originator and this isn’t great for the starfish gene pool!
There are around 1,500 different breeds of starfish living in our oceans and as a rule they are all resourceful, tough creatures which can regenerate and also lose limbs as a defence mechanism. Starfish in heavily fished waters are adept at “fixing” themselves in this way when they are damaged by nets or propellers.
Asexual Reproduction in Starfish
Asexual reproduction amongst starfish is through fission where the starfish’s central disc is split into two pieces or autotomy where one or more of the starfish’s arms are lost. Some starfish can regenerate from just a fragment of one arm. A single arm which has become separated from its host is known as a comet. Yet other species of starfish are able to reproduce asexually through their ability to release lava before they reach maturity…they do this when there is a very plentiful supply of food about and as a result are able to ensure more of their “offspring” will survive.
Any starfish in your aquarium which appear to have limbs which have grown at differing rates are most probably born of comets…single arms which have regenerated more arms or which have grown new limbs having lost one or more in an accident or a clash with a predator.
Starfish in your Aquarium
Whether you have purchased starfish especially for your tank or they’ve hitched a ride in…perhaps on some live rock, any decently sized set up can cope with a few pretty starfish inhabitants and they make great clean up crew too. There are of course many breeds to choose from with the most popular and easy to manage being the Brittle Starfish…a long limbed star with a small central disc. The Brittle Starfish is nocturnal and will come out during darkness to feed on whatever it can find on the bottom of your tank. As long as your aquarium has some rocks for this type of starfish to hide amongst, you will find them easy to keep in a saltwater aquarium.
Brown Asterinas are a commonly found starfish in many aquariums and they can easily get out of control as they multiply so quickly. They can also damage some corals so if you have any in your tank, do keep an eye out for what they’re eating and if they’re snacking on your prized corals, take them out with tweezers as a way of controlling the population.
Remember the basic rules before adding any new creature into your tank! Check that it looks healthy and feeds well and only buy from reputable sources.
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