Ursula species?
How many tentacles does she have in this one? I know she had 6, probably for budgetary reasons, in the animated version that led to some speculating she's a squid. How about in this one?
shareI read up on her (at least the animated version) on the Disney wiki, as well as reading about mermaid lore and coming across interesting artwork out there.
Ursula appears to by an "octomaid," a type of mer-person that is human-shaped from the waist up, but has octopus tentacles from the waist down instead of a fish tail. The male versions are often called "kraken" in monster/alien romance novels. Their appearance is far more variable than the females, often resembling fish men on top instead of "human" men.
Octomaids are not widely known about, so I'm guessing the animators wanted to branch out and make her more menacing than simply an ugly, undersea, mer-witch. Pat Carrol (the original voice actress) said that Ursula was a "cephalopod," but I find that term incorrect, because that's used for actual squids, cuttlefish, and octopi. It was said that she had octopus tentacles, but she only had 6 because her "human" arms counted among the 8.
You don't tend to come across very many octomaids in mermaid artwork, but I've seen them a few times. In the Saturday morning cartoon for Little Mermaid, Ariel once had to deal with an evil stingray man. So it's possible mer-people come in other forms than just the half human/half fish variety.