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Re: Prehistoric Plankton Predators (PPP for short)



Hi all

    It's interesting to me that you include Ocean Sunfish, Mola mola in this
group of giant plankton feeders.  Mola mola are giant plankton feeders in
that they eat giant plankton.    (I guess it's like the difference between a
"Maneating Chicken!"  and a man, eating chicken)  That is they feed on
jellyfish and colonial salps and such.  The odd arangement of huge vertical
dorsal and anal fins allows them to manuver around the perimenter of a big
jelly, munching away at the margin of the medusa bell as they go.  Unlike
some of the others listed in this catagory, they are plankton feeders to be
sure, but not filter feeders, or at least not very effective filterfeeders.
Their mouth is too small.

    On the other hand, most of the baleen whales are filter feeders, but not
really plankton feeders in the true sense of the word.  Grey Whales are
benthic feeders, scoping up mouthfulls of mud and filtering out whatever is
living in the mud, amphipods, polychete worms, molusks and such.  The big
Rorquels are feeding on krill and pelagic red crabs, which are free
swimming, schooling crusteceans, and schools of small fish like herring and
anchovy.  These can only be considered "plankton" by their relative size and
speed to their predetor, I suppose.  Humpbacks  actively concentrate schools
of fish by creating bubble nets   Fin Whales and Sei Whales do the same by
swimming circles around schools of fish and flashing their white bellys at
the school.  This is active hunting, not passive filtering.  If these guys
were really "plankton feeders" they wouldn't need to be so speedy and
manuverable.  Of all the Mysticetes, Bowheads and Right Whales come closest
to being true plankton feeders, and these have the longest and finest
baleen.  These are capable of cruising at slow speeds and filtering truly
tiny creatures such as copopods,  out of the water column.

And BTW, the biggest  predetory shark, Carcharodon megladon, evolved after
the K/T, about 40 Million years ago, probably in response to the evolution
and increasing sizes of whales.  -  Bill

Bill & Rebecca Hunt
Hunt Wildlife Studios
119 Bierstadt Ct
Livermore,  CO  80536
970-484-0894
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


> Are there any giant plankton-feeders from the Mesozoic? It really seems odd
> to me that throughout the Mesozoic, no animal seemed to take advantage of
> the plankton & grow to a huge size. Just look at our modern-day oceans:
> Among the elasmobranchs we have the Whale Shark (Rhincodon typus) the
> Basking Shark (Cetorhinus maximus) & the Megamouth Shark (Megachasma
> pelagios) the various species of Mobula & Manta rays, (Mobula sp. & Manta
> sp.) The teleosts have provided us with the Ocean Sunfish (Mola sp.), and
> let's not forget the 10-13 species of Mysticete or baleen whales.
> 
> If our modern oceans can support such a wide diversity of giant plankton
> feeders, why not the oceans of the Mesozoic? Surely the oceans then were
> just as bountiful; I cannot believe that the oceans of the Mesozoic were
> plankton-deficient. Or were the predatory marine reptiles & sharks so
> successful that large peaceful plankton-feeders could not evolve until they
> were wiped out after the K-T?
>