Echinodermata Circulatory System

Lesson Transcript
Instructor: Heather Pier

Heather has taught high school and college science courses, and has a master's degree in geography-climatology.

Explore the circulatory system of echinoderms, organisms in the phylum Echinodermata. Marvel at how they can have a circulatory system without a heart, and discover the features of their open circulatory system, known as a haemal system. Updated: 11/30/2021

A Circulatory System Without a Heart

Echinoderms are one of the true Frankenstein's of the animal world. If it wasn't strange enough that the members of phylum Echinodermata are able to have a nervous system without a brain and that their mouth and anus are sometimes the same body opening, it turns out that they are also able to have a circulatory system without a true heart. While it may be hard to believe that a mobile animal is able to move and function without a heart pumping blood throughout its body, that truly is the case with echinoderms.

The job of a circulatory system is to move nutrients, gases, and metabolic by-products through an animal's body, and allows for the removal of waste products and gases from the body. A heart is not actually a required part of a circulatory system.

It is also worth noting that while it is common to think of blood when you think of the circulatory system, not all animals have blood. Instead they directly exchange their nutrients and gases with the outside world through their body surfaces. Being blood-less is very common in soft bodied invertebrates like coral and jellyfish.

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  • 0:01 Circulatory System…
  • 1:09 A Circulatory System of Sorts
  • 1:52 Open Circulatory System
  • 2:48 Lesson Summary
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A Circulatory System of Sorts

Echinoderms do not have a true circulatory system like the ones found in humans or other mammals. Instead, they have a system of fluid-filled canals throughout their bodies that perform many of the functions that our circulatory systems do. These canals, referred to as an haemal system, is how they get the bad gases out of their bodies and the good gases in and help to transport blood and body fluids around the body cavity.

Their blood and fluids are pumped around their body by their water vascular system, which is found in all echinoderms. In addition to helping with motion and righting themselves, the water vascular system helps move their blood around by using changing fluid pressure.

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