’Community’ is one of those words that has different meanings in science & general use. Every time I set an essay that asks students to talk about biological communities, someone will tell me about ant communities, or monkey communities, or human communities. But a biological community is a group of populations from several different species, living & interacting in a particular area.
There are at least two schools of thought when it comes to considering the nature of a biological community. One is that the various species that make up a community have evolved together, & that a particular type of community will always have the same general makeup & structure. Another is what you could call an ‘individualistic’ model: members of any given community come together by chance. I was moved to write about this when I came across a website detailing the weird & wonderful members of a community based upon the decaying carcase of a dead sperm whale that lies 2900m below the surface of the ocean – surely one from the ‘individualistic’ end of the spectrum, as the community could form only when the whale’s corpse arrived at the bottom of the sea, & there’s surely no way of predicting when & where that might happen. (With the proviso, of course, that many colonisers may well arrive in larval form, dispersed widely throughout the water column, so there will be some species in common.) The particular community that’s the focus here includes hagfish**, snails, crabs, fish, crabs, sea anemones, octopuses - & of course, bone-eating worms!
Find another deceased & sunken whale, & you will almost certainly find a different assemblage of species. Ah, the wonders of the deep-ocean decomposition/recycling system! :-)
** Hagfish have neither jaws nor a bony skeleton, and the cartilagenous supporting rod called a notochord is retained throughout their life. They’re scavengers & produce large quantities of slime when handled, a characteristic that has seen them also dubbed ‘snot eels’. (‘Rock snot’ aka Didymo, snot eels, bone-eating snot-flowers – did those naming these various species have something of a preoccupation with nasal exudates??)