Phylum Echinodermata Research Paper
Phylum Echinodermata: Five main groups of echinoderms including brittle stars, starfish, echinoids, sea cucumbers, and sea lilies are individually sexed. Sexual reproduction is common because both males and females are present. It takes a few years for echinoderms to mature and get sexually mature.
Echinoderms do not require physical contact for the exchange of reproductive material instead they typically release their sperm and eggs into the water. Millions of individual sperm and eggs may be released at one time. Fertilization takes place when sperm and egg come contact each other while floating freely in the water.
Some echinoderms brood their eggs, especially in cold water species where planktonic larvae might not be able
to find sufficient food. These retained eggs are usually few in number and are supplied with large yolks to nourish the developing embryos. The female Star Fish carry the eggs in special pouches, under her arms, under her arched body or even in her cardiac stomach. Many brittle stars are hermaphrodites and egg brooding is quite common and usually takes place in special chambers on their oral surfaces, but sometimes the ovary or coelom is used. In starfish and brittle stars, direct development without passing through a bilateral larval stage usually takes place. Some sea cucumbers use their buccal tentacles for transfer of their eggs to their underside or back where they are retained. In other species, the eggs are remained in the coelom where they develop viviparously, later emerging through ruptures in the body wall. In some species of crinoid, the embryos develop in special breeding bags, in which the eggs are held until sperm released by a male happens to find them.
Advantages of Sexual Reproduction:
• Genetic recombination results in the formation of new traits.
• The resulting genetic diversity increases the changes of the species enabling them to survive sudden environmental changes.
• Variation leads to evolution.
• Sexually reproducing population eliminate deleterious and lethal mutations.
Echinoderms do not require physical contact for the exchange of reproductive material instead they typically release their sperm and eggs into the water. Millions of individual sperm and eggs may be released at one time. Fertilization takes place when sperm and egg come contact each other while floating freely in the water.
Some echinoderms brood their eggs, especially in cold water species where planktonic larvae might not be able
to find sufficient food. These retained eggs are usually few in number and are supplied with large yolks to nourish the developing embryos. The female Star Fish carry the eggs in special pouches, under her arms, under her arched body or even in her cardiac stomach. Many brittle stars are hermaphrodites and egg brooding is quite common and usually takes place in special chambers on their oral surfaces, but sometimes the ovary or coelom is used. In starfish and brittle stars, direct development without passing through a bilateral larval stage usually takes place. Some sea cucumbers use their buccal tentacles for transfer of their eggs to their underside or back where they are retained. In other species, the eggs are remained in the coelom where they develop viviparously, later emerging through ruptures in the body wall. In some species of crinoid, the embryos develop in special breeding bags, in which the eggs are held until sperm released by a male happens to find them.
Advantages of Sexual Reproduction:
• Genetic recombination results in the formation of new traits.
• The resulting genetic diversity increases the changes of the species enabling them to survive sudden environmental changes.
• Variation leads to evolution.
• Sexually reproducing population eliminate deleterious and lethal mutations.