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Evolution doesn't happen by chance. There must be selective pressure for certain traits to persist from generation to generation. In other words, if these traits become predominant in a species, there must be a reason for it that confers an adaptive advantage to the organism. So, why did it make sense for venom delivery systems to evolve the way they did in front-fanged snakes?
Heloderma are chunky, slow creatures. They trek long distances to find nests and eggs, leaving them vulnerable to predators. Thus the need arose for "keeping" venom: for defense. They also use it for digestion. In Komodo Dragons, they evolved complex venom glands for their "bite-and-slice" technique.
Strike-Induced Chemosensory Searching (SICS) is a stereotyped post-strike behavior that is utilized by many snakes and reptiles, but most prominently in vipers such as rattlesnakes.
After the snake strikes...
1. Quick, voluntary release of prey (to avoid counterattacks)
2. A quiescent period, allowing venom to incapacitate prey
3. Post-strike elevation in tongue flicking rate (PETF)
4. Locomotion while tongue flicking
5. Commencement of scent-trailing.
After the snake strikes...
1. Quick, voluntary release of prey (to avoid counterattacks)
2. A quiescent period, allowing venom to incapacitate prey
3. Post-strike elevation in tongue flicking rate (PETF)
4. Locomotion while tongue flicking
5. Commencement of scent-trailing.
Tongue - Chemoreceptor; flicks to gather odor molecules
Vomeronasal organ (Jacobson's organ) - Detects and relays molecules to the brain, opens when tongue retracts.
Envenomated prey - Tagged with unique chemical signature. Relocator proteins "tag" the prey, while released by metalloproteinases. Snakes can discern tagged prey from all others.
Vomeronasal organ (Jacobson's organ) - Detects and relays molecules to the brain, opens when tongue retracts.
Envenomated prey - Tagged with unique chemical signature. Relocator proteins "tag" the prey, while released by metalloproteinases. Snakes can discern tagged prey from all others.
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