chordates

Today fish is generally defined as chordates (vertebrates) minus tetrapods (four limbed things like amphibians, reptiles and mammals).

They're a subgroup of chordates, and so are closely related to us, but they've been brutally simplified over time.

The chordates retained them but the protostomes lost those features, so they are not a definitive proof of relationship.

Could there be billions of worlds with life that have yet to (or more likely failed to) even evolve chordates?

Tunicates and Echinoderms seem to have evolved from bilateral ancestors like the ancestors of chordates.

Vertebrates are one subphyllum of the chordates, not even the most diverse phyllum of animals.

The sea squirt larvae begin absorbing all the tadpole-like parts that made them chordates.

But there are some rather non-fishy chordates [1] so that doesn't work either.

Echinodermata [is the] second-largest grouping of deuterostomes (a superphylum), after the chordates...

A interesting footnote is the presence of possible chordate animals yet in that fauna (we are chordates as any other vertebrate).

While there are many genetic similarities between echinoderms+hemichordates and chordates (i.e.

It freaks me out that tunicates are chordates.

My comparison at that point would become "humans and zebras are basically chordates"...

The name "deuterostomes" is used for the ensemble of 2 groups, the chordates (including us) and a group composed of echinoderms and hemichordates (Ambulacralia).

Phylogenetically, there is also a relevant group, but we call them "chordates" instead.

Perhaps this could be rephrased in more common HN terms as "the octopus's genetic mechanism quite aggressively uses epigenetic mechanisms" or "calls genetic 'subroutines' in ways unfamiliar in chordates (like us).

Chordates are known for their chemistry weapons.

[b] In terms of taxonomy, we are Verterbrates [c] of the Synapsid clade (branch) [d] of Chordates.