Seastars
From Marine Aquariums of South Africa - wiki
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[edit] Seastars
[edit] Species Info
- Kingdom: Animalia
- Phylum: Echinodermata
- Subphylum: Asterozoa or Stelleroidea
- Class: Astroidea & Ophiuroidea
Echinodermata consists of Echinoderms which are made up of species of starfish, brittlestars, sea urchins, sea cucumbers and sand dollars.
Asterozoa/Stelloidae is a super class that consists of true sea stars (Astroidea), brittle stars (Ophiuroidea) and an extinct subclass called Somasteroidea.
[edit] Types of Seastars
Seastars are divided into the two following groups:
Astroidea: True sea stars, have no shape demarcation between their legs and main body. Movement is done via their numerous tube feet in each leg.
Ophiuroidea: Brittle stars have long arms clearly demarcated from the disc shaped body. Movement is accomplished by use of it's entire arm/s. Brittle stars are far more mobile than their true sea star cousins. There are over 1500 species of Brittle stars.
Seastars are quite strange creatures in the sense as they do not have a brain, eyes or a spine. Seastars have a complex nervous system which is able to interpret - light, temperature, touch and water parameters. They have no specific sensory organs (eyes, ears etc.) for these functions.
[edit] Feeding
Seastars are one of the most fascinating creatures in the marine trade/hobby and in turn collected extensively, most of the time to their own demise.
Seastars have two stomachs, one for normal digestion and the other is used to actually engulf and "digest" prey live.
Seastars have very specific dietary requirements and not all marine tanks can provide this.
Target feeding is required for the majority of species available in the marine hobby trade. The best way to target feed is place the feed next to the star and allow the creature to crawl on to the food. Handling seastars to target feed is not suggested, as the star will want to flee and won't be interested in feeding.
Seastars will slowly starve to death, so make sure you know what food they require !!
[edit] Stocking / Acclimation
Seastars require good acclimation. Sudden changes in water pH, Gravity or temperature can be fatal for these creatures. Best to make sure what water parameters the creature has come from and slowly (6-8hours) acclimatise the seastar to it's new home's parameters.
Generally the rule of thumb is one Asteroid per 100g (378 liters) of marine water. Ophiuroids can be kept in density of one per 50 liters but regular feeding will be required !
[edit] Aquarium requirements
Seastars available in the marine hobby/industry are generally scavengers. They feed off the leftovers from fishfood and detritus.
Due to this reason owners need to make sure they either target feed or have a big enough tank for these creatures to survive.
It is suggested that Live rock, caves and overhangs are provided for "quiet time" and totally necessary for reefgrazer stars like Brittlestars.
Seastars do not require any specific substrate conditions other than burrowing seastars, which will require a substrate to live in.
[edit] Lighting
Seastars have no specific lighting requirements and will thrive under any lighting provided.
[edit] Water Quality
Due to Seastars using their surrounding water in a pump-like system (at a molecular level) for movement and feeding, they are very sensitive to changes in water parameters.
It is known that Aquarists have lost seastars even from changing synthetic salt brands.
As like acclimation, If water parameters need to be changed, do it slowly.
[edit] What star ?
Stay away from the knobbly varieties of seatsars they tend to be predators or coral grazers.
The smooth armed Asteroids and Ophiuroid brittle stars are generally easier to keep and don't present risk to the tank's other inhabitants.
Species that are "easy" to keep:
Common Ophiurids - Serpent or Brittle Starfish, (excluding the Green Brittle Starfish due to it being a fish predator !) - great reef inhabitants that will keep the tank's live rock detritus free. Burrowing Sand Star - great for keeping your tank's substrate clean and tidy
[edit] Species that are difficult to keep:
Linckia, Leiaster, Fromia - make sure you know exactly what these species dietary requirements are. Also when selecting these creatures, check for injuries and any areas of discolouration.
If you can see any parasites on the seastar's body, stay away from these. It is almost impossible to rid a star of these parasites.
Check the star's movement and activity. Get the seller to move the star in a undesirable area (for the selected star).they not the quickest creatures around but you will see movement and the tube-feet extending.
