Echinoderms and jellyfish both are radially symmetrical unlike humans which are bilaterally symmetrical but still echinoderms are much more closely related to humans as compared to jellyfish. It is because echinoderms are deuterostomes just like humans which means that their anus is generated from the blastopore. In contrast to this, jellyfish is a protostome which means that its mouth is generated from blastopore. Radial symmetry is an important feature when it comes to comparing animals but being deuterostomes and protostomes is much more important when it comes to estimating evolutionary relationships of organisms.
Under these conditions an increase in the mutation rate evolves, which allows faster adaptation to the spatial variation in local temperature, causing a faster range expansion across the spatial gradient.
