摘要：SummaryAmphibians are known for their skin rich in glands containing toxins employed in passive chemical defense against predators, different from, for example, snakes that have active chemical defense, injecting their venom into the prey. Caecilians (Amphibia, Gymnophiona) are snake-shaped animals with fossorial habits, considered one of the least known vertebrate groups. We show here that amphibian caecilians, including species from the basal groups, besides having cutaneous poisonous glands as other amphibians do, possess specific glands at the base of the teeth that produce enzymes commonly found in venoms. Our analysis of the origin of these glands shows that they originate from the same tissue that gives rise to teeth, similar to the venom glands in reptiles. We speculate that caecilians might have independently developed mechanisms of production and injection of toxins early in their evolutionary history.Graphical AbstractDisplay OmittedHighlights•Amphibian caecilians have tooth-related glands in both upper and lower jaws•The glands have the same origin of reptile venom glands•The secretion contains proteins with enzymatic activities commonly found in venoms•Caecilians might have developed the ability to inject oral toxins early in evolutionBiological Sciences; Evolutionary Biology; Zoology
