Many aquatic animals possess elongated, cylindrical bodies, leading to their common misidentification as snakes. This article aims to clarify what these “snake-like fish” are, differentiating them from actual snakes and highlighting their unique adaptations.
Understanding the Difference
Snakes and fish belong to entirely different biological classes. A primary difference lies in respiration: fish breathe using gills, extracting oxygen from water, while snakes, as reptiles, possess lungs and breathe air. Snakes cannot survive submerged indefinitely, unlike fish.
Their outer covering also differs significantly. Fish scales are dermal in origin, forming from the skin’s deeper layer, and can be various types, often overlapping to provide protection and flexibility. Some fish, like most eels, have tiny scales embedded within their skin or are scaleless. In contrast, snake scales are epidermal, composed of keratin, forming tough, overlapping plates that create a dry texture.
Another clear distinction is the presence of fins. Fish typically possess dorsal, anal, caudal (tail), and paired pectoral and pelvic fins, which aid in movement and stability in water. Snakes, lacking these structures entirely, propel themselves through undulation of their bodies. Even elongated fish like eels may lack pelvic fins or have reduced pectoral fins, but they retain other fin structures.
Differences extend to their internal anatomy and reproductive strategies. Fish jaws and teeth vary widely depending on diet, while snakes have specialized jaw structures that allow them to swallow prey much larger than their heads. Fish generally lay eggs in water, though some species give live birth, whereas snakes lay eggs on land or give birth to live young.
Common Aquatic Animals Mistaken for Snakes
Many aquatic species have an elongated body form. Eels, such as moray eels and freshwater eels, are among the most recognized. They have long, flexible bodies and can be found in diverse habitats, from shallow ocean waters where they burrow into sand or mud, to freshwater rivers and streams.
Lampreys, ancient jawless fish, also have an eel-like appearance, characterized by a lack of paired fins and a distinctive round, sucker-like mouth lined with teeth. Their lifecycle often involves a larval stage filter-feeding in freshwater sediments, while adult forms can be parasitic or non-feeding. Hagfish are another group of jawless, eel-shaped creatures known for their scaleless, soft skin and ability to produce protective slime.
Loaches, typically bottom-dwelling freshwater fish, have narrow, elongated bodies and often have minute scales embedded in their skin. Pipefish, closely related to seahorses, are very slender, long-bodied fish covered in bony armor plates.
Needlefish are characterized by their long, slender bodies and elongated, needle-like jaws. They inhabit shallow marine environments, often near the surface, and some species are also found in brackish or freshwater. Snakehead fish, named for their flattened, snake-like heads, are predatory freshwater fish native to Asia. Snake eels, belonging to the family Ophichthidae, are named for their cylindrical, snake-like bodies. Many species lack fins, which facilitates burrowing into the substrate.
Where They Live and How They Behave
Snake-like fish inhabit nearly all aquatic environments. Eels, for instance, are found in both freshwater and saltwater, with many species burrowing into the substrate or hiding among rocks in shallow ocean areas. Some freshwater eels undertake extensive migrations to spawn in marine environments.
Lampreys typically inhabit coastal and fresh waters, with larvae burrowing into silt and sand bottoms. Hagfish are demersal, meaning they live on or near the bottom, preferring muddy seafloors in cold, deep waters where they often burrow. Loaches are primarily freshwater fish, residing in rivers and streams, with many species being bottom-dwellers that forage in the substrate.
Pipefish and needlefish generally occupy shallow coastal waters, including seagrass beds, or are found near the surface of the open sea. Snakehead fish are native to freshwater habitats across Asia, often found in slow-moving or stagnant waters like ponds and swamps. Snake eels inhabit tropical to warm temperate waters globally, with many species burrowing into mud or sand.
Their elongated body shapes influence their behavior. Many snake-like fish, such as hagfish, some eels, loaches, and snake eels, use their slender bodies to burrow into sediment, providing shelter. Some eels can even move short distances over land, using their bodies to wiggle across wet surfaces. Pipefish, despite their appearance, are relatively weak swimmers, relying on rapid movements of their dorsal fin for propulsion.
Feeding behaviors also vary among these species. Hagfish and some eels are scavengers, consuming dead organisms, while many eels, needlefish, and snakeheads are active predators. Lamprey larvae are filter feeders, but adult lampreys can be parasitic, attaching to other fish. Many species, including eels and loaches, exhibit nocturnal activity patterns, feeding during the night and seeking shelter during the day.
Identifying and Interacting Safely
Distinguishing snake-like fish from actual snakes involves observing key characteristics. Fish, even those with elongated bodies, will possess gill slits or covers for respiration, which snakes lack. While some fish may have reduced or fused fins, the presence of any fin structure, particularly a caudal (tail) fin, indicates it is a fish, as snakes have no fins whatsoever. Observing the animal’s movement in water can also offer clues; fish typically undulate their entire bodies to swim, while snakes may exhibit different movement patterns depending on the species and environment.
When encountering any unfamiliar aquatic animal, maintain a safe distance. Observe these creatures from afar and avoid attempting to touch or handle them. Respecting their natural environment by not disturbing their habitats or interfering with their behaviors contributes to personal safety and the animal’s well-being.