Echinodermata

Vivian Park

Hello to all you love-seekers! I’m of the phylum Echinodermata. My kind includes starfishes, sea urchines, sea biscuits, and many more!

Better known for fossil records, this phylum has app. 7000 living species and about 13,000 extinct species.

I’m a small species, even when I’ve matured, but one thing that’s different about me is that I am radically symmetrical as an adult, while bilateral as a larva.

I live in water and have come to develop a unique water vacular system. This is used for locomotion, repiration and feeding.I have a simple hemal and excretory system. My nervous system is also decentralized.

If you’re looking for a cute small, water-loving phylum, you’re looking at her right now!

I am a benthic organism that can be found in marine environments. My kind, echinoderms, are the only phylum group with no freshwater or land animals. Some of them can even survive drying when washed on the shore.

A starfish, an example of enchinoderm, cling to rocks, and prefer a rocky environment. However, other echinoderms might prefer sandy area where they can burry themselves in order remain concealed. Or live in the mud. Many Echinoderms also use other animals as homes such as sponges or the skin of other fishes.

I prefer a changeless environment, including that of pH, salinity, and light. Since I feed at night, I also prefer a place where I can stay concealed throughout the day.

My favorite activity is to sleep and eat. There are many feeding methods us echinoderms use such as active, omnivorous scavenging, selective predation, or mud swallowing.

I am good with hunting a prey, holding them down with my tubed feet. Then I tend to break my prey open using hydrostatic suction. By inserting my stomach into my prey, I can digest them and then suck them up. I mostly feed on small suspended organisms.

As much as I love eating, I can also survive several weeks without any nutrition. I am also able to get a great amount of nourishment from the organic matter dissolved in the sea water through outer layer of my body.

Scientist believe that we evolved a great deal in the Precambrian era.  However, because they are not certain of its fossil records, due to the lack of information and resources available to them, they can only speculate.

It has been suggested that the triradiate condition may have been a precursor of pentamerous symmetry. Scientists also speculate that the lack of Precambrian fossil echinoderms indicates that while the earliest echinoderms may have possessed a water-vascular system, they lacked a calcite skeleton and thus did not fossilize.

Ancient echinoderms exhibited an extraordinary variety of bizarre body forms; the earliest classes seemed to be “experimenting” with body shapes and feeding mechanisms; most were relatively short-lived.

We are some of the most distinctive animals, based on their four morphologies.  The first is that all echinoderms have a calcitic skeleton that is composed of many ossicles.  The ossicles have a stereom, which is a sponge-like microstructure, that is very unique.  These ossicles act as an exoskeleton, although they are truly an endoskeleton since they're produced by mesenchymal cells.

The second characteristic that we have that make them unique is a water vascular system.  This system is used for locomotion, respiration and feeding.

The third unique characteristic that we have is mutable collagenous tissue.  Ligaments that are made of collagen, connect the ossicles in echinoderms.  This connective tissue is mutable, whereas most ligaments are tight but can be loosened temporarily.  Because of this characteristic, echinoderms can maintain different positions without much effort.

The last unique characteristic that echinoderms have is a pentaradial body organization in adults.  This means that they are radial symmetrical with five arms.  Echinoderm's level of symmetry changes from the larvae stage to the adult stage.  When they are larvae they have bilateral symmetry and as adults they have radial symmetry.

While I can go through internal fertilization, I can also go through a sexual reproduction process that is usually separated between male and female echinoderms.  My eggs will be laid in the water, and the males spermatozoa will also be laid in the water where the eggs are then fertilized.

I can have asexual reproduction, which usually involves the division of two parts of my body or regeneration of a missing arm.  We are the first invertebrates where the female broods the tiny stars.

I’m looking for a male echinoderm that can produce many spermatozoa and aid in producing as many offspring as possible.

Works Cited

"ADW: Echinodermata: Information." Animal Diversity Web. 24 Apr. 2009 <http://animaldiversity.ummz.umich.edu/site/accounts/information/Echinodermata.html>.

Biodiversity Project 2004. <http://www.personal.psu.edu/awt5004/sharedtaxonomicfeatures.htm>.

"Echinoderm." Brittanica. Tree of Life Web Project. 24 Apr. 2009

<http://tolweb.org/>.