- The larvae of many echinoderms, especially starfish and sea urchins, arepelagic(of
or pertaining to the open ocean). How does this relate to the fact that echinoderms
are distributed globally?
Further Reading / Supplemental Links
- http://dictionary.reference.com
- http://www.oceanicresearch.org/education/wonders/echinoderm.html
- http://www.junglewalk.com/info/echinoderm-information.htm
- http://invertebrates.si.edu/echinoderm/http://en.wikipedia.org
Vocabulary
echinodermata The phylum of the echinoderms; contains about 7,000 living species, the
largest phylum without freshwater or terrestrial members.
nerve net Interconnected neurons that send signals in all directions.
pelagic Of, or pertaining to, the open ocean.
sessile Permanently attached and not freely moving.
water vascular system A network of fluid-filled canals; functions in gas exchange, feed-
ing, and also in locomotion.
Points to Consider
- Echinoderms’ water vascular system functions in gas exchange via a network of fluid-
filled canals. Terrestrial arthropods have internal surfaces that are specialized for gas
exchange, via air sacs. How might these systems compare and differ? - Echinoderms possess an open and reduced circulatory system, consisting of a central
ring and five radial vessels but no heart. Arthropods also have an open circulatory
system but the blood is propelled by a series of hearts into the body cavity where it
comes in direct contact with the tissues. Why might there be an advantage to having
a heart as part of the circulatory system?