Amphibians: There are 31 species of amphibians found in the Big Thicket area, including 11 species of salamanders and 20 species of frogs and toads. Some of the more commonly encountered salamanders in the region include the smallmouth salamander ("Ambystoma texanum"), dwarf salamander ("Eurycea quadridigitata"), and central newt ("Notophthalmus viridescens"). The three-toed amphiuma ("Amphiuma tridactylum") is one of the larger salamanders in the world and can grow over . Three salamanders, including the three-toed amphiuma ("Amphiuma tridactylum"), Gulf Coast water dog ("Necturus beyeri"), and lesser siren ("Siren intermedia"), retain their gills from the larva stage and live their entire lives in the muddy waters of east Texas and consequently, although not rare, are seldom seen except by an occasional fisherman or those who specifically go look for them. Likewise, mole salamanders (members of the genus "Ambystoma"), including the spotted salamander ("Ambystoma maculatum"), marbled salamander ("Ambystoma opacum"), mole salamander ("Ambystoma talpoideum"), and tiger salamander ("Ambystoma tigrinum") spend much of their lives underground and are infrequently seen except for few short weeks each year during their breeding seasons. The southern dusky salamander ("Desmognathus auriculatus"), once widespread in Southeast Texas, now appears to be in serious decline.