The oyster toadfish (''Opsanus tau''), also known as the oyster toad, ugly toad, oyster cracker, oyster catcher, and bar dog, is a Northwest Atlantic species of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

of the family Batrachoididae. The maximum length of this toadfish is , but they infrequently surpass . The world record size for this species is 19.2 inches which is 48.76 cm. They are generally yellowish with a pattern of brown oblique bars. The species can live in poor conditions and needs little food to live. They can be found near the shore from

Maine Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

. In 1998,

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

sent the oyster toadfish into space to investigate the effects of

microgravity Weightlessness is the complete or near-complete absence of the sensation of weight, i.e., zero apparent weight. It is also termed zero g-force, or zero-g (named after the g-force) or, incorrectly, zero gravity. Weight is a measurement of the fo ...

on the development of

otolith An otolith (, ' ear + , ', a stone), also called otoconium, statolith, or statoconium, is a calcium carbonate structure in the saccule or utricle (ear), utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule ...

ic organs. The study found little difference between terrestrial development and those in space.

Life history

Spawning and life cycle

Oyster toadfish spawn in coastal estuaries from May through August, with some variation between latitudes. Males excavate nests under rocks or other debris and begin making advertisement calls, also known as boatwhistles and foghorns. Females are attracted to these calls. Females choose a mate, enter the nest, attach eggs to the underside of the structure, then leave. Females provide no

parental care Parental care is a behavioural and evolutionary strategy adopted by some animals, involving a parental investment being made to the evolutionary fitness of offspring. Patterns of parental care are widespread and highly diverse across the animal k ...

. Males fertilize the eggs, then defend and clean the nest while embryos develop. Toadfish embryos are large and, as a result, have been studied for over a century. After about 4 weeks the eggs hatch. At first, the young toadfish stay attached to the

yolk Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...

. When the yolk has been absorbed for energy, the young toadfish learn to swim. Even when the young have started to swim, the adult still protects its young. Juveniles reach sexual maturity at 2–7 years and have a lifespan of 8 years. Little is known about individual range or whether toadfish exhibit natal philopatry.

Predators and prey

Toadfish are ambush predators during the day, when they remain buried or hidden under structure and lunge for passing prey. At night they forage. Toadfish eat benthic invertebrates (e.g. polychaetes) and xanthid crabs. Toadfish have sharp teeth and powerful jaws. Oyster toadfish are

apex predator An apex predator, also known as a top predator or superpredator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the hig ...

s on oyster reefs. Nonetheless, evidence exists that they are prey for birds (e.g. cormorants). A related species, ''Opsanus beta'', is prey for dolphins. Research has demonstrated that toadfish will call less when dolphin sounds are played from a nearby speaker. For protection, toadfish have a venomous spine in the first ray of the dorsal fin. They can bury themselves up to their eyeballs in sand, and might be capable of camouflage.

Physiology

Like many

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

oyster toadfish have a

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

that is used to maintain buoyancy. Like some vocalizing fish, the swim bladder is also used to make sounds. Oyster toadfish males use their swimbladders to make advertisement calls. The fast-twitch swimbladder muscles of toadfish can contract as much as 300 times per second, more quickly than fast-twitch muscles in most vertebrates.

Model for hearing and behavior

Toadfish are easy to observe and collect because they spawn in shallow water. Also, male advertisement calls are easy to detect and are critical for the animal's reproductive success. For these reasons, toadfish have been widely studied in research that examines mating behavior, hearing sensitivity and the impacts of anthropogenic noise.

Cuisine

Oyster toadfish are hard to fillet due to their bony bodies. The meat of the oyster toadfish is flaky and is described as having a sweet flavor, similar to that of blowfish.

References

External links

Hear the foghorn-like sound of the oyster toadfish, fro

the NASA experiment

more NASA {{Authority control Opsanus Fauna of the Eastern United States Fish of the Atlantic Ocean Fish described in 1766 Taxa named by Carl Linnaeus