Toadfish
Encyclopedia
Batrachoididae is the only family
in the ray-finned fish order
Batrachoidiformes. Fish in this family are usually called toadfish
: both the English common name and scientific name refer to their toad
-like appearance (batrakhos is Greek
for frog).
Toadfish are benthic ambush predator
s that favor sandy or muddy substrates where their cryptic
coloration helps them avoid detection by their prey. Toadfish are well known for their ability to "sing", males in particular using the swim bladder as a sound-production device used to attract mates.
and premaxilla
, and often decorated with barbels and skin flaps. They are generally drab in colour, although those living coral reefs may have brighter patterns. They range in size from 7.5 centimetres (3 in) length in Thlassophryne megalops, to 57 centimetres (22.4 in) in the Pacuna toadfish.
The gills are small and occur only on the sides of the fish. The pelvic fins are forward of the pectoral fins, usually under the gill
s, and have one spine with several soft rays. There are two separate dorsal fin
s; the first is smaller with spines, while the second has from 15 to 25 soft rays. The number of vertebrae range from 25 to 47.
Toadfishes of the genus Porichthys, the midshipman fish
es, have photophore
s and four lateral line
s. All toadfishes possess sharp spines on the first dorsal fin and on the opercle (gill cover). In fish of the subfamily Thalassophryninae, these are hollow and connect to venom glands capable of delivering a painful wound to predators.
, though some are found in brackish water and one subfamily, the Thalassophryninae, is found exclusively in freshwater habitats in South America
. In particular, Daector quadrizonatus and Thalassophryne amazonica are known from the Atrato River
in Colombia
, and the Amazon River
, respectively.
s, crustacean
s, mollusks
and other fish. They often hide in rock crevices, among the bottom vegetation, or even dig dens in the bottom sediments, from which they ambush their prey. Toadfish can survive out of water for as much as 24 hours, and some can move across exposed mudflats at low tide using their fins.
Males make nests, and then attract females by "singing", that is, by releasing air by contracting muscles on their swim bladder. The sound has been called a 'hum' or 'whistle', and can be loud enough to be clearly audible from the surface. The eggs are sticky on one side, so that the female can attach them to the side of the nest. Each male will attract numerous females to his nest, so that the eggs within will have multiple different mothers.
The male then guards the nest against predators. During this period, the male must survive on a limited supply of food, as they are not able to leave the immediate vicinity to hunt. The eggs rapidly develop into embryos, but these remain attached to the side of the nest until the age of about three to four weeks. After this time, they continue to cluster around and hide behind the male, until they are large enough to fend for themselves. This degree of parental care is very unusual among fishes.
Order Batrachoidiformes
The western Atlantic species Opsanus tau known as the oyster toadfish
is quite widely used as a research animal, while a few species, most notably Thalassophryne amazonica, are occasionally kept as aquarium fish
.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
in the ray-finned fish order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Batrachoidiformes. Fish in this family are usually called toadfish
Toadfish
Batrachoididae is the only family in the ray-finned fish order Batrachoidiformes. Fish in this family are usually called toadfish: both the English common name and scientific name refer to their toad-like appearance .Toadfish are benthic ambush predators that favor sandy or muddy substrates where...
: both the English common name and scientific name refer to their toad
Toad
A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin , short legs, and snoat-like parotoid glands...
-like appearance (batrakhos is Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
for frog).
Toadfish are benthic ambush predator
Ambush predator
Ambush predators or sit-and-wait predators are carnivorous animals that capture prey by stealth or cunning, not by speed or necessarily by strength. These organisms usually hide motionless and wait for prey to come within striking distance. They are often camouflaged, and may be solitary...
s that favor sandy or muddy substrates where their cryptic
Crypsis
In ecology, crypsis is the ability of an organism to avoid observation or detection by other organisms. It may be either a predation strategy or an antipredator adaptation, and methods include camouflage, nocturnality, subterranean lifestyle, transparency, and mimicry...
coloration helps them avoid detection by their prey. Toadfish are well known for their ability to "sing", males in particular using the swim bladder as a sound-production device used to attract mates.
Description
Toadfishes are usually scaleless, with eyes set high on large heads. Their mouths are also large, with both maxillaMaxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
and premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
, and often decorated with barbels and skin flaps. They are generally drab in colour, although those living coral reefs may have brighter patterns. They range in size from 7.5 centimetres (3 in) length in Thlassophryne megalops, to 57 centimetres (22.4 in) in the Pacuna toadfish.
The gills are small and occur only on the sides of the fish. The pelvic fins are forward of the pectoral fins, usually under the gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s, and have one spine with several soft rays. There are two separate dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s; the first is smaller with spines, while the second has from 15 to 25 soft rays. The number of vertebrae range from 25 to 47.
Toadfishes of the genus Porichthys, the midshipman fish
Midshipman fish
The midshipman fishes are the genus Porichthys of toadfishes. They are distinguished by having photophores and four lateral lines...
es, have photophore
Photophore
A photophore is a light-emitting organ which appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors...
s and four lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
s. All toadfishes possess sharp spines on the first dorsal fin and on the opercle (gill cover). In fish of the subfamily Thalassophryninae, these are hollow and connect to venom glands capable of delivering a painful wound to predators.
Distribution and habitat
Most toadfish are marineMarine biology
Marine biology is the scientific study of organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather...
, though some are found in brackish water and one subfamily, the Thalassophryninae, is found exclusively in freshwater habitats in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. In particular, Daector quadrizonatus and Thalassophryne amazonica are known from the Atrato River
Atrato River
The Río Atrato is a river of northwestern Colombia. It rises in the slopes of the Western Cordillera and flows almost due north to the Gulf of Urabá , where it forms a large, swampy delta....
in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, and the Amazon River
Amazon River
The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
, respectively.
Habits and reproduction
Toadfishes are bottom-dwellers, ranging from near shore areas to deep waters. They tend to be omnivorous, eating sea wormSea worm
Sea worm is a general term that may refer to a number of phyla of animals, or may refer specifically to:*Acanthocephala, parasitic worm*Annelida, segmented worms*Chaetognatha, arrow worms*Cycliophora, lobster worms*Entoprocta*Echiura, spoon worms...
s, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, mollusks
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
and other fish. They often hide in rock crevices, among the bottom vegetation, or even dig dens in the bottom sediments, from which they ambush their prey. Toadfish can survive out of water for as much as 24 hours, and some can move across exposed mudflats at low tide using their fins.
Males make nests, and then attract females by "singing", that is, by releasing air by contracting muscles on their swim bladder. The sound has been called a 'hum' or 'whistle', and can be loud enough to be clearly audible from the surface. The eggs are sticky on one side, so that the female can attach them to the side of the nest. Each male will attract numerous females to his nest, so that the eggs within will have multiple different mothers.
The male then guards the nest against predators. During this period, the male must survive on a limited supply of food, as they are not able to leave the immediate vicinity to hunt. The eggs rapidly develop into embryos, but these remain attached to the side of the nest until the age of about three to four weeks. After this time, they continue to cluster around and hide behind the male, until they are large enough to fend for themselves. This degree of parental care is very unusual among fishes.
Genera
There are about 80 species of toadfish, grouped into 21 genera, as follows:Order Batrachoidiformes
- Family Batrachoididae
- Subfamily Batrachoidinae
- Genus Allenbatrachus (3 species)
- Genus Amphichthys (3 species)
- Genus Austrobatrachus - Puzzled toadfish (1 species)
- Genus Batrachoides (9 species)
- Genus Batrachomoeus (5 species)
- Genus Batrichthys (3 species)
- Genus Bifax - Two-faced toadfish (1 species)
- Genus Chatrabus (2 species)
- Genus Colletteichthys - Flat toadfish (1 species)
- Genus Halobatrachus - Lusitanian toadfish (1 species)
- Genus Halophryne (4 species)
- Genus Opsanus (6 species)
- Genus Perulibatrachus (3 species)
- Genus Potamobatrachus (1 species)
- Genus Riekertia - Broadbodied toadfish (1 species)
- Genus SanopusSanopusSanopus is a genus of fish in the Batrachoididae family. They are restricted to the Atlantic coast of Central America and Mexico.It contains the following species:* whitespotted toadfish * bearded toadfish...
(6 species) - Genus Thalassothia (1 species)
- Genus Triathalassothia (2 species)
- Genus Vladichthys (1 species)
- Subfamily Porichthyinae
- Genus Aphos (1 species)
- Genus Porichthys - Midshipmen (14 species)
- Subfamily Thlassophryininae
- Genus Daector (5 species)
- Genus Thalassophryne (6 species)
- Subfamily Batrachoidinae
Economics
Toadfish are not normally commercially exploited, however, they are taken by local fishermen as a food fish, and by trawlers where they usually end up as a source of fishmeal and oil. Some smaller toadfish from brackish-water habitats have been exported as fresh-water aquarium fishes.The western Atlantic species Opsanus tau known as the oyster toadfish
Oyster toadfish
The oyster toadfish, Opsanus tau, also known as the ugly toad, oyster cracker and "bar dog", is a fish of the family Batrachoididae. The maximum length of the toadfish is about 38 cm; the most common recorded length of an oyster toadfish is about 30 cm...
is quite widely used as a research animal, while a few species, most notably Thalassophryne amazonica, are occasionally kept as aquarium fish
Fishkeeping
Fishkeeping is a popular hobby concerned with keeping fish in a home aquarium or garden pond. There is also a fishkeeping industry, as a branch of agriculture.-Types of fishkeeping systems:...
.