Toad Fish: Habitat And Characteristics
The term “frogfish” does not refer to a single species of animal within the actinopterygium class, but rather encompasses all those belonging to the Batrachoididae family , in turn located in the order Batrachoidiformes. This group includes a total of 83 species, in turn divided into 21 different genera. All of them have certain common characteristics.
Along these lines, we are going to focus on the Lusitanian toadfish ( Halobatrachus didactylus ), the only member of its genus, with an appearance similar to that of other better known representatives of the Batrachoididae family . If you want to know more about this species and other relatives, keep reading.
Toadfish habitat
Toadfish, as a family, are found throughout the globe. Most of the species collected in this taxon are marine, although many of them live in intermediate saline waters. The exception to the rule is the Thalassophryninae subfamily , with representatives that inhabit only fresh waters in rivers of South America —especially the Amazon—.
For its part, the Lusitanian toadfish ( Halobatrachus didactylus ) is distributed throughout the eastern Atlantic Ocean —from Portugal to Ghana— and the Mediterranean. It has also been introduced in the northern part of Spain due to natural movements, probably due to the warming of the waters. As indicated by the Xunta de Galicia , the first sighting in this region dates from 2018.
This fish lives shallow – about 100 meters from the surface, normally between 10 and 50 meters – on sandy and rocky bottoms. As we will see in later lines, its coloration allows the animal to completely blend in with the typical environment at the bottom of the Mediterranean water column.
Physical characteristics
In general, toadfish lack scales and carry large, flattened heads. Their mouths are also very prominent, with highly developed maxillae and premaxilas. Appendages or barbels usually hang from the lower region of the mouth , sensory organs that help these animals locate food in murky waters where vision is not useful.
On the other hand, the gills are small and lateralized. These fish also have pectoral and pelvic fins, which in turn are supported by spines and various soft rays. For its part, the Lusitanian toadfish has 2 spines covered by the skin in the upper corner of the operculum and 2 dorsal fins.
The first of these dorsal fins has 3 strong covered spines, while the second is supported by 19-24 long, smooth rays. In addition, the skin of this species lacks scales – like the rest of frogfish – and is covered by a characteristic mucus . Its color is light brown with dark spots that form patterns and its maximum size is 55 centimeters.
Behavior of the Lusitanian toadfish
The Lusitanian toadfish is a sedentary animal that is normally found in substrates formed by sand, rocks and mud. In addition to its cryptic tone, this fish remains partially buried to the bottom most of the time, only exposing its more prominent fins and head region. In this position, it waits for its prey to pass in front of it.
Fish capable of making sounds
Beyond its habits with respect to the environment, this fish stands out a lot above the rest for its ability to perform vocalizations. In addition, according to studies published on the scientific portal FISH Biology, the sounds emitted vary according to the time of year. During mating, males make hissing-type sounds, while other vocal registers appear year-round.
This behavior is believed not to be present in the earliest stages of development. The emission of sounds seems to begin when the juveniles are capable of generating grunts with a higher sound level and a lower dominant frequency.
Feeding
The toadfish is solitary and remains half-buried in the bottoms or in the crevices of the stones most of its life. It feeds mainly on mollusks, crustaceans and other small fish, which is why it is considered a predatory species. Its strategy is of the sit and wait type , as it simply waits for the victim to walk by and engulf it with its large head apparatus.
On the other hand, it should be noted that this species is of minor importance in the fish trade for food purposes. Despite being known in the southern areas of Spain, these animals are not usually consumed in the field of gastronomy.
Reproduction of toadfish
According to a study published in the scientific journal General and Comparative Endocrinology, this species has a reproductive cycle that spans from March to August, with a peak between May and June. During this time, males produce special vocalizations, thanks to the use and contraction of their swim bladder. These serve to attract females or to avoid conflicts with other males.
Receptive males attract females to their nests or places of residence. If these have been “convinced” by the vocalizations, they will release the eggs to the outside, where an external fertilization takes place. These eggs are sticky on one side and adhere perfectly to the male’s nest, which will protect them until they hatch.
State of conservation and final notes
As indicated by the International Union for Conservation of Nature (IUCN), this species is considered of “Least Concern (LC)” as far as conservation is concerned. Some populations are established in protected areas and are not exploited for consumption in the market, so there are no real dangers that could kill them immediately.
If something stands out above many other species, it is the ability of the Lusitanian toadfish to produce vocalizations in their mating season and beyond. This feature has attracted the interest of scientists and the general public alike.
