Worldbuilding Stack Exchange is a question and answer site for writers/artists using science, geography and culture to construct imaginary worlds and settings. It only takes a minute to sign up.
Sign up to join this community
Ray-finned fishes have a variety of interesting and complex jaw structures.
Here is the skeleton of an anglerfish
Here is the skull of another actinopterygian
I am designing a large (roughly sturgeon-sized) deep-sea predatory fish. What jaw structure would be best suited for creating large suction forces to draw its prey into its mouth from a distance of several feet?
It depends on how they live.
https://en.wikipedia.org/wiki/Actinopterygii
Actinopterygii (/ˌæktɪˌnɒptəˈrɪdʒiaɪ/), or the ray-finned fishes, constitute a class or subclass of the bony fishes.[1]
Numerically, actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish.[2] They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 mm (0.3 in), to the massive ocean sunfish, at 2,300 kg (5,070 lb), and the long-bodied oarfish, at 11 m (36 ft).
I think the angler fish catches prey like its cousin the bass - a sudden gulp. Teeth are to prevent prey from escaping. A bluefin tuna has a jaw like a tiger and teeth to match - for chasing down and catching active prey. Ocean sunfish suck up jellyfish.
In a group as successful, ancient and diverse as these ocean-conquering fish you will have a huge range of lifestyles and adaptations. Which tool is the most efficient, a screwdriver or a pop rivet gun or a claw hammer? Efficiency only makes sense in the context of a given task.
16 letters, 2 words: Dunkleosteus jaws.
Dunkleosteus terrelli is a species of large predatory placoderms which occupied the niche of Apex predator in the Devonian seas. This was allowed both to their large size and, more importantly, due to its powerful Jaws. The peculiarity of said Jaws is that they allowed for dunkleosteus to have both a powerful bite and a large opening, with its Jaws being able to open up 45 degrees in 60 milliseconds. This allowed for it to create a strong enough vacuum to pull its prey inside its mouth, letting its scissor-like Jaws finish it. Your predator could likely have a very similar design, as the fact that it only went extinct after the devonian extinction event wiped it out, so it was clearly very successful.
The kind they already have
Actinopterygian evolution can be described as one long progression from the ancestral fixed-jaw condition seen in the oldest fishes (and retained in sharks, sarcopterygians, bichir) to the highly protrusible jaws seen in extant Perciformes. By turning the premaxilla into a mobile, protrusible element, fish are able to create a greater suction force which makes them more easily able to suck in prey in an aquatic environment. It's less useful for larger prey, but in those cases like barracudas and pike these fishes have re-evolved a fixed-jaw useful for snagging larger prey. Or they just get an even bigger head to such down even bigger food like catfishes and grouper do. So a large, deep-sea predatory fish would have a protrusible premaxilla similar to almost every other large, predatory teleost. It wouldn't be anything unique.
