Morgan Hunt
December 27, 08
H Biology A
Asteroidea Reproduction
Star fish are both sexual and asexual, depending on how you think of it.
Most reproduce sexually. Each arm holds a pair of gonads that become almost filled with eggs or sperm during the time of breeding. Most species are broadcast spawners, which means eggs and sperm are released into the water column to be fertilized. To increase the chances of fertilization, sea stars come together when they are ready to spawn. The crown-of-thorns sea star, releases a potent chemical into the water column to attract the opposite sex. As for the Asterias Rubens, the female produces small eggs that are released into the sea and fertilized externally to develop as planktotrophic larvae. Eventually, they go through metamorphosis and settle on the seabed to grow into adults. This type of reproductive strategy is known as indirect-development.
Some sea stars brood their young. Females hold their fertilized eggs in a brood space either under the arm, in the stomach, or keep them warm in the gonads. If they are kept in the stomach or gonads, they develop within and escape through small openings the female's body wall called gonopores.
However, seven species (that tend to be very small) are known to willingly pinch off one or more arms that then redevelop a complete new disc and arms.
Freeman, S. (n.d). Asteroidea (Sea Stars). In Answers. Retrieved December 27, 2008, from http://www.answers.com/topic/asteroidea-sea-stars-biological-family.
Friday, June 5, 2009
MAKE ONE FOR THIS!!!!!!!!
2) Physical Description
-general
-more detail with the two species
2) Physical Description
-general
-more detail with the two species
2) Physical Description
-general
-more detail with the two species
2) Physical Description
-general
-more detail with the two species
-general
-more detail with the two species
2) Physical Description
-general
-more detail with the two species
2) Physical Description
-general
-more detail with the two species
2) Physical Description
-general
-more detail with the two species
Basic Overview
Basic Overview-
The starfish that I’m studying fall in the kingdom Animalia, the Phylum Echinodermata and the subclass of Asteriodea. These species are grouped into these seven orders: Brisingida, Forcipulatida, Notomyotida, Paxillosida, Spinulosida, Valvatida and Velatida.. There are roughly 1500 different species in the Asteroidea class. However, to us, they are just simply starfish. They are considered the ‘true starfish’. Basically they are just central disks with five broadly arms connected to it.
Two starfish in which I will go into further detail are the Asterias rubens and the crown-of-thorns starfish Acanthaster planci. Both are very different. The Asterias rubens are what most consider the common starfish, and the Acanthaster planci is a very different, unique starfish that most wouldn’t even realize is a starfish.
Asteroids are marine animals that are found in all the oceans. They live in just about any habitat in the ocean; such as tidal pools, rocky shores, sea grass and kelp beds, beneath rock rubble, on coral reefs, sand, and mud. The are seafloor predators. They have certain attributes which allow them to withhold rough conditions. The fact that they can suction allows them to stay stuck in seabeds or close to shore although there are crashing waves.
Mulcrone, R. 2005. "Asteroidea" (On-line), Animal Diversity Web. Accessed November 02, 2008 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Asteroidea.html.
The starfish that I’m studying fall in the kingdom Animalia, the Phylum Echinodermata and the subclass of Asteriodea. These species are grouped into these seven orders: Brisingida, Forcipulatida, Notomyotida, Paxillosida, Spinulosida, Valvatida and Velatida.. There are roughly 1500 different species in the Asteroidea class. However, to us, they are just simply starfish. They are considered the ‘true starfish’. Basically they are just central disks with five broadly arms connected to it.
Two starfish in which I will go into further detail are the Asterias rubens and the crown-of-thorns starfish Acanthaster planci. Both are very different. The Asterias rubens are what most consider the common starfish, and the Acanthaster planci is a very different, unique starfish that most wouldn’t even realize is a starfish.
Asteroids are marine animals that are found in all the oceans. They live in just about any habitat in the ocean; such as tidal pools, rocky shores, sea grass and kelp beds, beneath rock rubble, on coral reefs, sand, and mud. The are seafloor predators. They have certain attributes which allow them to withhold rough conditions. The fact that they can suction allows them to stay stuck in seabeds or close to shore although there are crashing waves.
Mulcrone, R. 2005. "Asteroidea" (On-line), Animal Diversity Web. Accessed November 02, 2008 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Asteroidea.html.
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