The common mudpuppy, Necturus maculosus, is a large, fully aquatic salamander native to North American rivers, lakes, and permanent ponds. It is notable for retaining its bushy, reddish external gills throughout its life, a trait known as neoteny. This species can grow to an average length of 13 inches and typically hides under rocks and logs during the day. The mudpuppy is a nocturnal predator, and its diet reflects its nature as a bottom-dwelling, opportunistic carnivore.
Natural Prey and Primary Food Sources
The wild diet of the mudpuppy is diverse and relies heavily on the availability of slow-moving aquatic organisms in its habitat. These salamanders consume a variety of invertebrates, with crayfish frequently identified as a major component of their food intake. Aquatic insects and their larvae, such as mayfly nymphs, also form a large part of the diet. Other common invertebrate prey include mollusks, such as snails and small clams, as well as annelids like aquatic worms and earthworms. The mudpuppy’s opportunistic feeding extends to small vertebrates, including small fish, fish eggs, and the eggs and larvae of other amphibians. They also scavenge on carrion, using their sense of smell to locate dead organisms.
Hunting Strategy and Sensory Perception
Mudpuppies are nocturnal, hunting most actively under the cover of darkness when prey is easier to ambush. Their strategy relies on stealth and a specialized feeding mechanism rather than fast pursuit. The primary method of capturing prey is known as suction feeding, or the “suck and gape” technique. This action involves the salamander rapidly opening its mouth to create a sudden vacuum, drawing water and the nearby prey item directly inside. Their small, conical teeth are used for holding the captured prey to prevent its escape before it is swallowed whole. The ability to find prey in dark or murky water is supported by a sophisticated lateral line system, a series of specialized sensory pores in the skin. This system detects subtle changes in water pressure and vibrations caused by the movement of potential prey, allowing the mudpuppy to precisely locate its meal without relying on sight.
Diet Variation Based on Size and Season
The mudpuppy’s diet shifts significantly throughout its lifespan and across seasons. Juvenile mudpuppies, which are smaller, primarily consume smaller prey items like micro-crustaceans, small insect larvae, and zooplankton. As they grow into adults, their diet transitions to larger, more energetically rich items such as crayfish and small fish. Seasonal changes in water temperature and prey availability also influence feeding behavior. During the warmer summer and fall months, the diet may consist almost exclusively of various invertebrates. In the colder winter and spring months, mudpuppies often incorporate vertebrate prey like fish into their diet. This shift to larger, high-calorie food items during colder periods is linked to an improvement in the salamander’s overall body condition.
Feeding Mudpuppies in Captivity
Maintaining a captive mudpuppy requires providing a diet that closely mimics its natural carnivorous intake while ensuring nutritional balance. Earthworms, specifically nightcrawlers, are recommended as they offer a complete source of nutrition. Other acceptable food sources include frozen and thawed items such as bloodworms, brine shrimp, or pieces of fish fillet. Adult mudpuppies have a relatively slow metabolism in the cool water they require (typically 50–68°F or 10–20°C), and therefore do not need to be fed daily. A feeding schedule of two to three times per week is sufficient for an adult, while juveniles require food more frequently, about four to five times weekly. It is important to avoid using certain feeder fish, such as goldfish and minnows, as a staple diet. These fish contain the enzyme thiaminase, which breaks down Vitamin B1 (thiamin) and can lead to a severe thiamine deficiency in the mudpuppy.