Toothless jaws covered with dark, keratinized sheaths. Males and females indistinguishable externally. Larva differs from older individual by having more extensive tail fin and distinctive orange-red markings that include head stripe from gill to gill by way of snout, band across back of head, and stripe down middle of back. Aquatic and nocturnal inhabitants of swamps, ditches, lowland ponds, and sloughs. In seasonally dry bodies of water, they descend into burrows, produce a cocoon from skin gland secretions, and estivate until water returns.
Adults eat worms, snails, and crayfish.
Little is known about courtship and mating. Maturation probably requires 3-4 years. Underwater microphones have detected clicking sounds produced by sirens when they approach each other. May be even more widespread than thought, but infrequently seen because of secretive habits.