Toxins are non-living
biological and chemical agents produced by living microorganisms from animals
and plants that can cause harm to humans, plants and animals. An example of
toxin is botulinum toxin produced by the bacterium Clostridium, which is a
neurotoxic protein that prevents the release of the neurotransmitter
acetylcholine from axon endings at the neuromuscular junction and causes
flaccid paralysis.
Moreover, toxin are more
closely related to chemical warfare agents that can only affect those who are
exposed to the agent and that they are not considered as transmissible disease.
Sharp teeth that are constantly replaced would be the answer! In order for it to be a specific adaptation you would need the detail of why the animal has that adaption for example fins for stability:)