Why are echinoderms closely related to chordates?

Answer 1

most chordates are vertebrates, but some are not. invertebrate chordates belong to two of the subphylum of chordates. Cephalochordata and Urochordata. both invertebrate and vertebrate chordata have a dorsal nerve cord, a notochord, pharyngeal pouches and a postanal tail.

Answer 2

Jeffries' Hypothesis is based upon archaelogical findings that show that ancestral echinoderms HAD 4 of the 5 chordate hallmarks: A notochord, dorsal nerve chord, pharyngeal gill slits, and the post-anal tail. These ancestral echinoderms were named calcichordates and it moves echinoderms closer to chordata rather than hemichordata. Mainly because it has the 4 hallmark features and is missing the the 5th which is the endostyle (homologous thyroid gland).

Hemichordata only have 2 of the hallmark characteristics: Pharyngeal gill slits and a hollow nerve cord. This would be the 2nd hypothesis that chordates are related to hemichordates but it seems to be in less favor.

The third hypothesis is that chordates are most related to hemichordata AND echinoderms.

In archaeological findings and ontogeny and phylogenic trees, we see pharyngeal gill slits then hollow dorsal nerve cords, then the endostyle, then the post-anal tail, and then notochords in Chordate development....

I personally like Jeffries' Hypothesis but all 3 are possible. It is science after all... thus hypotheses will be present until proven guilty.

Answer 3

Both evolved in the Cambrian period and in water.

Answer 4

Vertebrates (v) and chordates (c) are the same thing, the difference is vertebrate have a notochord in a very beginning stage whereas chordates have it all their life.

Answer 5

Insects are a subdivision of arthropods. They have jointed bodies.

Answer 6

"look up burgess shale and it will explain everything and then all you have to do is relate them to eachother...it gives u all of the info"

Answer 7

This is because they're embryology is very similar to that of a vertebrates. Also their internal skeletons, and their phylum is the most closest related to vertebrates

Answer 8

Outstanding similarity in Arthropods & fungus is presence of chitin in both groups

Answer 9

In Latin, Echinodermata tranlates to "spiny skin". So, all echinoderms have spiny skin. Also, most echinoderms have radial symmetry, except the sea cucumber which has bilateral symmetry.

Answer 10

They both present exoskeletons and have segmented bodies.