Echinodermata
Echinodermata, (the latin word meaning spiny-skinned) have several characteristics:
Radial Symmetry
Several arms radiating from a central body
tentacle-like structures called tube feet with suction pads
Echinoderms are exclusively marine-animals. They can regenerate missing limbs, arms, spines .Echinoderms are protected through their spiny skins and spines. But they are still preyed upon by shells , some fish, and other echinoderms like the carnivorous starfish.
Radial Symmetry
Several arms radiating from a central body
tentacle-like structures called tube feet with suction pads
Echinoderms are exclusively marine-animals. They can regenerate missing limbs, arms, spines .Echinoderms are protected through their spiny skins and spines. But they are still preyed upon by shells , some fish, and other echinoderms like the carnivorous starfish.
Echinodermata Circulatory System
Echinoderms have an open circulatory system with cilia circulating the fluids through each arm. Echinoderms have a network of fluid-filled canals that function in gas exchange, feeding and in movement. The network contains a central ring and areas which contain the tube feet which stretch along the body or arms. The tube feet poke through holes in the skeleton and can be extended or contracted. They do not have a true heart.
Starfish Circulatory System
Starfish also have no true heart or anything that more than merely resembles a circulatory system. Starfish have a well structured system of tubes that works in place of the circulatory system.
Sand dollar Circulatory System
The sand dollar does not have a circulatory, respiratory, or excretory systems, It has a network of water-filled canals called the water vascular system to help move & feed.
•it's powered by the movement of water through the canals. •Contracting muscles cause the water to continuously move throughout these canals
•it's powered by the movement of water through the canals. •Contracting muscles cause the water to continuously move throughout these canals
Sea Cucumber Circulatory System
Like all
echinoderms, sea cucumbers possess both a water vascular system that provides
hydraulic pressure to the tentacles and tube feet, allowing them to move, and a
haemal system. The haemal system is more complex than that in other echinoderms, and
consists of well-developed vessels as well as open sinuses. The blood fills the water vascular system.