Beetles are like the MVP of species (minimum viable, not most valuable). Some superstructure (which can often double as armor) plus food storage. Even crabs are extravagant next to a beetle: crab takes that recipe and adds on attack capabilities, which are sometimes wasteful (crabs attacking humans are wasting their time for example).
Life: beetles, plus extra features which must be justified.
There are tons of other insect groups that could be very easily described as similarly "minimum viable" that don't have nearly the diversity. Abundance of some group doesn't necessarily correlate with the speciation within that group. Ants are an exceptionally successful type of insect with orders of magnitude fewer described species.
I’d like to suggest the swap of oyster in the place of clam, because oysters are less mobile than clams.
This leads to a funny observation: for some reason I think a worm and an oyster are obviously animals, like if you were a caveman with no notion of genetics or the tree of life and you came across either, I suspect you’d think “this thing is obviously some kind of animal.” But a sponge is not so obvious, I think, to our hypothetical caveman. I could believe a sponge is a weird plant.
I think you need at least one distinguishing feature beyond the minimal to become obviously an animal, for some reason.
When digging in sand, they are also surprisingly quick. You can see when they spout water out of their little holes in the sand, but if you don’t start digging like crazy they can easily get away.
Clamming was a surprisingly fun way to waste a morning as a kid, it is like playing at the beach with objectives. If you ever happen across somebody with a license, I suggest giving it a try.
More like "without knowledge of the particular choices made by prominent biologists".
The roots of "animal", "fungus", and "plant" are completely arbitrary; anything outside the chosen root can be called a "protist" (many marine "plants" are counted as protists nowadays).
Compared to the mammal template, beetles don’t have to do satisfy as many requirements (no temperature regulation, simple brains, etc). So they can have complicated biochemical attacks because they have a solid foundation, easy to build on.
It is definitely possible I haven’t thought this out very well.
> Beetles are like the MVP of species (minimum viable, not most valuable).
Dude... There are water beetles that live underwater, but do also fly and walk. This is not "mininum viable" in any sense of the term. Just because they have smaller brains and less developed immune systems does not mean that they are millions of years beyond mammals in fantastic specialization!
Life: beetles, plus extra features which must be justified.