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Starfish laid eggs.. At least, I think that's what has happened?
I recently added a small red fromia starfish to my tank. I have had it for about a week and noticed small red beads floating around in the tank. They looked like they came out of the centre of the starfish. Now the starfish is moving but has certainly not been as active as when I first put it in. Should I be doing anything with the eggs/starfish?
Last edited by nelletron; 04-18-2013 at 12:21 AM. |
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Quote:
Most species of starfish are dioecious, there being separate male and female individuals. These are usually not distinguishable externally, as the gonads cannot be seen, but their sex is apparent when they are spawning. Some species are simultaneous hermaphrodites (producing eggs and sperm at the same time). In a few of these, the same gonad, called an ovotestis,[45] produces both eggs and sperm. Yet other starfish are sequential hermaphrodites, with some species being protandrous. In these, young individuals are males that change sex into females as they grow older, Asterina gibbosa being an example of these. Others are protogynous and change sex during their lives from female to male. In some species, when a large female divides, the smaller individuals produced become males. When they grow big enough, they change back into females.[46] Each arm contains two gonads, which release gametes through openings called gonoducts, located on the central disc between the arms. Fertilization is external in most species, though a few show internal fertilization. In most species, the buoyant eggs and sperm are simply released into the water (free spawning) and the resulting embryos and larvae live as part of the plankton. In others, the eggs may be stuck to the undersides of rocks to develop.[47] In certain species of starfish, the females brood their eggs – either by simply enveloping them [47] or by holding them in specialised structures. These structures include chambers on their aboral surfaces,[48] the pyloric stomach (Leptasterias tenera)[49] or even the gonads themselves.[45] Those starfish that brood their eggs by covering them usually raise their disc and assume a humped posture.[50] One species broods a few of its young and broadcasts the remaining eggs which cannot fit into the pouch.[48] In these brooding species, the eggs are relatively large, and supplied with yolk, and they generally, but not always,[45] develop directly into miniature starfish without a larval stage. The developing young are called "lecithotrophic" because they get their nutrition from the yolk, as opposed to planktotrophic feeding larvae. In one species of intragonadal brooder, the young starfish obtain their nutrition by eating other eggs and embryos in their gonadal brood pouch.[51] Brooding is especially common in polar and deep-sea species that live in environments less favourable for larval development [35][49] and in smaller species that produce few eggs.[52] Reproduction occurs at different times of year according to species. To increase the chances of their eggs being fertilized, starfish may synchronize their spawning, aggregating in groups [47] or forming pairs.[53] This latter behaviour is called pseudo-copulation [54] and the male climbs onto the female, placing his arms between hers, and releases sperm into the water. This stimulates her to release her eggs. Starfish may use environmental signals to coordinate the time of spawning (day length to indicate the correct time of the year, dawn or dusk to indicate the correct time of day), and chemical signals to indicate their readiness to each other.[55] In some species, mature females produce chemicals to attract sperm in the sea water.[55]
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Tags |
eggs, fromia, red beads, starfish |
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