Transcript Carnivorous Plants and Insects

•Background
•Protocarnivorous
plants
•How they trap
insects
•How they evolved
•“Plants that derive some or most of their
nutrients (but not energy) from trapping and
consuming animals, typically insects and other
arthropods”.
•Acidic bogs, rock outcroppings
•Around 625 species that are true carnivores
•Lack ability to directly digest or
absorb nutrients from prey
•Rely on bacteria or internal
food webs
•Darlingtonia californica 
•Relies on symbiotic bacteria
and protozoa
Five trapping mechanisms:
•Pitfall traps (pitcher plants)
•Flypaper traps
•Snap traps
•Bladder traps
•Lobster-pot traps
•Rolled leaves with enzymes or
bacteria in a pool of liquid
(phytotelmata) at base
•Insects attracted by nectar
“bribes”
•Sides are slippery
•Some have downward pointing
hairs
•Other mechanisms to trap prey –
false exits
•Utilise mucilage – polar glycoprotein
used as glue
•Secreted by glands on leaf
•Can be projected (Drosera capensis), or
flat (Pinguicula gigantea)
•Leaves curl around prey to stop escape
– thigmotrophic growth
• Drosera burmanii can bend 180° in ~
1min
•Leaves divided into two lobes, hinged
along the middle
•Trigger hairs in the lobes sensitive to
touch
•Action potential to midrib
•Ions pumped out creating osmotic
gradient
•Cells collapse, lobes under tension,
snap shut
•Continuous stimulation keeps lobes
shut, encourages growth
Bladder Traps:
Lobster-pot Traps:
•Exclusive to genus
Utricularia
(bladderworts)
•Easy to enter chamber
•Ions pumped out of
bladders
•Small hinged opening
releases vacum
•Escape hindered by bristles,
or hard to find exit
•Prey forced to move down
chamber
•Water movement
Hairy-leaf theory:
•All traps are based on hairy leaves and folding
•Hairs trap water droplets, insects drown in water
•Bacteria decompose, nutrients absorbed into leaves
•More water held, selective advantage  pitfall traps
•Bladder traps originate from aquatic plants with pitfall traps