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Echinoderms are characterized by radial symmetry, several arms (5 or more, mostly grouped 2 left - 1 middle - 2 right) radiating from a central body (= pentamerous). The body actually consists of five equal segments, each containing a duplicate set of various internal organs. They have no heart, brain, nor eyes, but some brittle stars seem to have light sensitive parts on their arms. Their mouth is situated on the underside and their anus on top (except feather stars, sea cucumbers and some urchins).
Echinoderms have tentacle-like structures called tube feet with suction pads situated at their extremities. These tube feet are hydraulically controlled by a remarkable vascular system. This system supplies water through canals of small muscular tubes to the tube feet (= ambulacral feet). As the tube feet press against a moving object, water is withdrawn from them, resulting in a suction effect. When water returns to the canals, suction is released. The resulting locomotion is generally very slow.
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What is a characteristic of Echinoderms?
Invertebrate animals with spikes and spines all over their bodies.
Do protists have tube feet?
No, tube feet are a characteristic feature of echinoderms, such as sea stars and sea urchins. Protists do not possess tube feet.
Why are echinoderms thought to have evolved from bilaterally symmetrical ancestors?
Echinoderms are thought to have evolved from bilaterally symmetrical ancestors because their larval forms exhibit bilateral symmetry. Over time, echinoderms undergo a process called pentaradial symmetry, where they develop a five-point radial symmetry characteristic of adult echinoderms. This suggests a modification from bilateral to radial symmetry during evolution.
System that allows echinoderms to move eat and breathe?
Echinoderms do not have a respiratory system similar to a person's. Instead, they have a water vascular (otherwise known as "ambulacral") system, made up of a network of canals to move water. This method accounts for the creature's gas exchange, feeding, and locomotion. Because of this characteristic, echinoderms lack gill slits.
Do echinoderms have deuterostome development?
Yes, echinoderms exhibit deuterostome development. In deuterostomes, the first opening that forms during embryonic development becomes the anus, while the mouth develops later. Echinoderms, such as sea stars and sea urchins, share this characteristic with other deuterostomes, including chordates. Additionally, they display radial symmetry and a unique water vascular system.
Why do zoologist think that pentaradial symmetry was not present in the ancestor of echinoderms?
Zoologists believe that pentaradial symmetry was not present in the ancestor of echinoderms because this symmetry is a derived characteristic that evolved later in their evolutionary history. The ancestral echinoderms likely exhibited bilateral symmetry, similar to their closest relatives, such as chordates and other deuterostomes. Fossil evidence and comparative studies of living echinoderms suggest that the transition to pentaradial symmetry occurred after the divergence from their bilateral ancestors, as a response to their marine environments and ecological adaptations.
What kingdom are echinoderms in?
Echinoderms are in the Animalia kingdom.
What is the scientific name for Echinoderms?
The scientific name for Echinoderms is Echinodermata.
What phylum do echinoderms belong to?
Echinoderms belong to the phylum Echinodermata.
Do echinoderms have a 5 part radial symmetry?
Yes, echinoderms exhibit a unique form of body symmetry known as pentamerous radial symmetry, which is typically organized around a central axis and divided into five parts. This characteristic is most evident in adult forms, such as starfish, which have five arms radiating from a central body. However, some echinoderms can have variations in the number of arms, but the underlying symmetry remains based on the five-part arrangement. This symmetry is a key feature that distinguishes echinoderms from other animal groups.
Echinoderms are parasitic or not?
As of yet, there is no known species of parasitic echinoderms.
Do echinoderms live in salt water?
Yes Eventually echinoderms do live in water.
