Friday, April 15, 2011

Sea Star Spawn and so on

Sea stars, and many other marine animals, reproduce in ways that look very different from anything air dwellers do. Recent visitors to our Puget Sound Salt Water Tide Pool may have noticed some interesting, springtime behavior.

If you notice a sea star emitting a cloudy substance, the star is spawning - releasing its gametes into the water. Sea stars can be either male or female, and both release their spawn (is there a better word for this?) in the same way. Because they tend to live near other members of their species, there is a very good chance that some of these cells will find each other and fertilization can take place. In our tide pool, with its necessary filtration system, any fertilized sea star eggs won't be able to survive.

Like sea stars, many anemone species spawn by releasing free swimming (gametes) into the water. But many anemones also reproduce asexually, creating genetically identical clones of themselves. They can either split into two anemones of roughly equal size, or the parent anemone can bud smaller offspring. Sometimes when a large anemone relocates, it will leave small groups of cells that regenerate into tiny new anemones.

When you visit our tide pool or take a walk on a beach, lives are being lived around you. Look closely to appreciate the many way animals have evolved to meet the challenges of survival and reproduction.

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