Greater Siren

Greater sirens play a crucial role in aquatic food webs and have been described as midlevel predators. Sirens swallow molluscs whole and will pass the shell as waste. They are nocturnal and spend the day in dense vegetation. Their lifespan in the wild is unknown, but in captivity they can live up to 25 years. Greater sirens can vocalize, producing clicks or yelps sounding similar to the call of the American green tree frog. and might last as long as three years in large individuals with high lipid content. They are also capable of trimodal respiration, with gas exchange occurring across branchial, cutaneous, and pulmonary surfaces. Known predators include the American alligator and the mud snake.

Their spermatozoa possess a pair of flagella, and their courtship behavior is unknown. After the eggs have been laid, the father will continuously fan its tail back and forth over or through the nest. The father will aggressively guard the nest from potential threats, including other sirens, and even the mother of the clutch. After 2 months, the eggs hatch, and the fathers depart from the nest. Youth live in shallower water than adults, often among the roots of water hyacinths.

Greater sirens inhabit the coastal plain from Washington, D.C., to Florida and Alabama. Associated habitat for greater sirens includes vegetative ditches, and various other forms of slow, or stagnant bodies of water. Often during the day, they seek refuges from predators and are found under logs and various other structures.

=== Trapping techniques === S. lacertina is difficult to capture because of their preference for areas with thick vegetation. Standard methods such as dip-netting, seining, and dredges are ineffective in such habitats. The use of aquatic funnel traps, commercially produced to capture crayfish, has been found effective for use on Siren and Amphiuma species and there is no risk of drowning the animals. Each trap consists of the trap body, three funnels, and a neck with a lid at the top.

Greater sirens are classified as Least Concern by the International Union for Conservation of Nature, although they have been extirpated from some of their former range due to habitat loss. They are protected under Mexican law and are assigned to the "Special Protection" category.