What is the Difference Between Chordates and Echinoderms?

Chordates and echinoderms are two distinct groups of animals that belong to the deuterostomes, a superphylum of animals based on their embryonic development. They share some common features but also have significant differences.

Similarities:

• Both chordates and echinoderms are deuterostomes, which means they share a similar pattern of early development.

Differences:

• Symmetry: Echinoderms have radial symmetry, meaning they can be divided into equivalent parts along the center and have only a defined top and bottom. Chordates, on the other hand, have bilateral symmetry, which means they can be divided into a left and right half, and have a defined top, bottom, front, and back.
• Skeletal Structure: Echinoderms have a dermal skeleton, similar to an exoskeleton or a shell-like structure, composed of calcareous ossicles. Chordates, including humans, have an endoskeleton made up of bones and cartilages.
• Nervous System: Echinoderms have a decentralized neural net without any central point, while chordates have a central nervous system, called a notochord or a neural tube. In many chordates, the end of the notochord is enlarged to form a defined, centralized brain, which is not present in echinoderms.
• Circulatory System: Echinoderms possess a water-based circulatory system, with the madreporite as the point of entry and exit for water for the water vascular system. Chordates, including vertebrates, have a closed circulatory system with blood as the circulatory fluid.
• Feeding: Echinoderms usually feed on plankton and other small organisms using their tube feet. Chordates, including humans, have a variety of feeding mechanisms, such as suction feeding, filter feeding, and biting and chewing.
• Locomotion: Echinoderms move using their tube feet. Chordates, including humans, use legs, fins, or wings for locomotion.
• Reproduction: Echinoderms exhibit sexual reproduction, with separate sexes and fertilization occurring outside the body. Chordates, including humans, also exhibit sexual reproduction, but with internal fertilization in many cases.

Comparative Table: Chordates vs Echinoderms

Here is a table comparing the differences between chordates and echinoderms:

Chordates are bilaterally symmetric and have an endoskeleton made up of bones and cartilages. They are present in all biomes and usually have locomotion by legs, fins, or wings. In contrast, echinoderms are radially symmetric (pentaradial) and have an exoskeleton made of calcareous ossicles. They are exclusively marine organisms and move using tube feet.