Answer:
There are two major characteristic differences are -
Dolphin and squid are triploblastic while jellyfish is diploblastic,
Dolphin and squid have complex organ systems whereas jellyfish lack it.
Explanation:
Jellyfishes are multicellular, marine organisms of the phylum Cnidaria. Dolphin is a vertebrate organism that belongs to Mammalia. They produce young ones, have complex organ systems. Squids are also marine organism belongs to mollusks. They have 8 arms and tentacles.
Both squid and dolphin are triploblastic (3 germ layers) and having complex organ systems, while jellyfish is diploblastic (2 germ layers) and absence of complex organ system.
