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Re: Prehistoric Plankton Predators (PPP for short)

Thanks for all the help. Guess Leedsichthys slipped my mind. So it seems that lamniform & orectolobiform sharks evolved planktivorous forms in the Late Cretaceous.

By the way, I don't think that krill were necessary in order to sustain giant filter-feeding planktonivores; I was trying to visualise a creature much like our modern day whale shark, a giant inhabitant of warm tropical waters, not the mysticete whales living in frigid polar seas. I think that back then, there was still plenty of plankton floating about in the seas; copepods & ostracods, the nauplii & larvae of various crustaceans & fish; if ammonite young were planktonic, that would be an additional boost. Let's not forget that today, many fish spawn en masse, or that giant clams & hard corals synchronise their spawnings to create a rich planktonic 'soup' surely a bonanza to any animal with the adaptations to filter out the good stuff.

I agree that it is likely that some prehistoric marine reptiles were facultatively planktonivorous. The leopard & crabeater seals, which feed on krill but do not filter it out (in the strictest sense) came to mind. Also, I watched this documentary where a blue shark was swimming through a swarm of krill, taking large bites out of the red cloud. Maybe cryptoclidids & other plesiosaurs, with their interlocking teeth, did take advantage of planktonic blooms.

But I'm just wondering whether predation may have had any effect on giant plankton feeders; Are there any records of giants like whale sharks, basking sharks & manta rays being attacked by say, great white sharks or orcas? Just imagine... a Leedsichthys cruises along when a Liopleurodon rises out of the deep & before the fish can react, the reptile bites it into half, turning the sea red & attracting pterosaurs & sharks for miles around. What I would give to see that...

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