The anglerfish is one of the most recognizable creatures of the deep ocean, often pictured as a fearsome, bulbous predator. Its most distinctive feature is the bioluminescent lure, used to attract prey in the abyssal zone. This terrifying image often leads to the assumption that the animal must be enormous, yet the reality of its size, when compared to a human, is far more complex and surprising. The true size depends entirely on the species and the sex of the individual fish.
Understanding Anglerfish Diversity
The term “anglerfish” refers to the entire order Lophiiformes, which includes over 300 different species inhabiting a wide range of depths. These species are broadly categorized into two main groups based on where they live: the benthic, or bottom-dwelling, species and the pelagic ceratioid, or deep-sea, anglerfish. The benthic species, such as the European monkfish, live on the continental shelf and can reach lengths of up to two meters, making them larger than the average human. The iconic, terrifying image most people associate with the anglerfish belongs to the ceratioid group, which lives in the open water of the deep sea. To fully understand the size comparison, it is necessary to focus on the dimensions of these ceratioid females, as they are the largest and most visually dramatic members of the group.
Scale Comparison to the Average Human
The majority of deep-sea anglerfish species are significantly smaller than the popular imagination suggests, rarely growing to the size of a human torso. The typical female of many deep-sea species, such as the Black Seadevil, measures around 20 to 30 centimeters in length, which is roughly the size of a small football.
Even the largest-known deep-sea anglerfish, a female Krøyer’s deep-sea anglerfish (Ceratias holboelli), only reaches a maximum length of about 1.2 meters, or just under four feet. This size is comparable to a large dog or a small human child. In terms of weight, even these largest deep-sea specimens are relatively light, rarely exceeding 50 pounds, a fraction of the weight of an average adult human.
The perception of their immense size largely comes from their disproportionately large head and mouth. The jaw is lined with long, fang-like teeth, allowing the fish to swallow prey larger than itself whole. When seen up close, the gaping maw and fearsome teeth contribute to the creature’s oversized reputation. In reality, the overall body mass of even the largest deep-sea anglerfish is dwarfed by an adult person.
Size Extremes in Anglerfish Mating
The anglerfish size comparison is further complicated by one of the most extreme cases of sexual dimorphism found in the animal kingdom, which is a significant difference in size between males and females. The deep-sea female, which is the basis for most size comparisons, is many times larger than her mate. The male anglerfish is a tiny, streamlined creature whose sole purpose is to locate a female for reproduction.
Once the male finds a female, he bites onto her body, and in many species, he permanently fuses to her tissue. This process, known as sexual parasitism, causes the male to degenerate, losing his eyes and internal organs, and his circulatory system merging with the female’s. This tiny male is then reduced to little more than a pair of gonads, providing a constant source of sperm whenever the female is ready to spawn.
The size difference is astonishing, with females sometimes being up to 60 times the length and a half-million times the mass of the male. The smallest known sexually mature male anglerfish, from the species Photocorynus spiniceps, measures a mere 6.2 millimeters long. This minuscule size means the male is comparable in scale to a human thumbnail, making him one of the smallest known vertebrates in the world.