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Re: Prehistoric Plankton Predators (PPP for short)

 "Dino Rampage"  wrote:
> 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.

Leopard Seals are the top predetors under the Antarctic Ice, feeding on
Emperor and Adelie Penguins.  I don't think that they feed on krill at all.
Crabeater seals do feed on krill and their multi cusp teeth seem to be
evolving for that purpose, straining krill out of the seawater.

> I watched this documentary where a blue shark was swimming through a swarm
> of krill, taking large bites out of the red cloud.

Yeah, I saw that footage too,  more proof that there are no hard and fast
rules, or that when there are some critter is bound to break them.  "Swarm
of Krill" is the correct description too.

>Maybe cryptoclidids &
> other plesiosaurs, with their interlocking teeth, did take advantage of
> planktonic blooms.

Ceardactylus, Tropeognathus and Anhanguera all appear to have interlocking
teeth for catching or straining small fish or squid.  And Pterodaustro
certainly appears to have bristles akin to baleen for straining even smaller
organisms, like Flamingos do today.
> 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?

Oh Yeah.  There are reports of Orcas cooporative/pack hunting several
species of baleen whales.  They take bites out of the lips and tongue of
their hapless victim.  There is even film footage of Orcas swimming along
side of a Blue Whale, taking large chunks of flesh from the flanks and back.
Still photos of this incident appeared in National Geographic a few years
ago.  There is speculation that the rise of Orcas may have replaced and
caused the decline of Carcharodon megladon.  Taking over that niche, Orcas
being a more effective and efficient killer and eater of large whales.  -

Bill & Rebecca Hunt
Hunt Wildlife Studios
119 Bierstadt Ct
Livermore,  CO  80536
e-mail;  bill@huntstudios.com
Web;  http://www.huntstudios.com

"A human being should be able to change a diaper, plan an invasion,
butcher a hog, conn a ship, design a building, write a sonnet, balance
accounts, build a wall, set a bone, comfort the dying, take orders, give
orders, cooperate, act alone, solve equations, analyze a new problem, pitch
manure, program a computer, cook a tasty meal, fight efficiently and die
gallantly.  Specialization is for insects." -- Robert A. Heinlein