The footballfish are a family

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...

, Himantolophidae, of globose, deep-sea anglerfish

Anglerfish

Anglerfishes are members of the teleost order Lophiiformes . They are bony fishes named for their characteristic mode of predation, wherein a fleshy growth from the fish's head acts as a lure; this is considered analogous to angling.Some anglerfishes are pelagic , while others are benthic...

es found in tropical and subtropical waters of the Atlantic

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

, Indian

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, and Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. The family contains c. 19 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 all in a single genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, Himantolophus (from the 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;...

 imantos, "thong, strap", and lophos, "crest").

Physical description

As in other deep-sea anglerfish families, sexual dimorphism

Sexual dimorphism

Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 is extreme: the largest females may exceed lengths of 60 cm (two feet) and are globose in shape, whereas males do not exceed 4 cm (1.5 inches) as adults and are comparatively fusiform. Their flesh is gelatinous, but thickens in the larger females, which also possess a covering of "bucklers" — round, bony plates each with a median spine

Spine (zoology)

A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin...

 — that are absent in males. Both are a reddish brown to black in life.

In females, the mouth is large and oblique. The subequal jaws are anteriorly lined with rows of numerous close-set, depressible, and retrorse teeth

Tooth

Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

; vomer

Vomer

The vomer is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.-Biology:...

ine teeth are absent. Footballfish females differ from those of other ceratioid families by their shortened, blunt snout; along with the chin, it is covered in sensory papillae. Originating above or slightly in advance of the small eye

Eye

Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...

 is an ilicium (the "fishing rod") and at its end a bioluminescent

Bioluminescence

Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...

, bulbous esca (the "fishing lure", its light owing to symbiotic

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 bacteria). Escal morphology varies between species, and it may or may not possess denticles or accessory appendages, the latter either branched or unbranched. The pterygiophore of the ilicium does not protrude from the snout, and there is no hyoid barbel

Barbel (anatomy)

A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...

.

At maturity, the streamlined males have an enlarged posterior nostril

Nostril

A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...

 (with 10 – 17 lamellae); slightly ovoid eye with an enlarged pupil

Pupil

The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In...

 creating a narrow anterior aphakic

Aphakia

Aphakia is the absence of the lens of the eye, due to surgical removal, a perforating wound or ulcer, or congenital anomaly. It causes a loss of accommodation, hyperopia, and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma.Aphakic people are...

 space; no ilicium or esca; and the head and body is covered in dermal spinules, those along the snout midline being enlarged. The jaw lacks teeth, whereas those of the denticular bone have fused into a larger mass; the upper denticular bone possesses 10 – 17 hooked denticles.

In both sexes, the fins are spineless: the single 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...

 with 5 – 6 soft rays, the pectoral fins with 14 – 18, the anal fin with four, and the caudal fin with 19. There are six branchiostegal rays and 19 vertebrae; the parietal

Parietal

Parietal may refer to:*Parietal placentation*Parietal lobe of the brain*Parietal bone of the skull*Parietal scales of a snake lie in the general region of the parietal bone*Parietal cell in the stomach*Parietal pleura...

 is lacking throughout life, there are no epurals, and the pelvic bone is triradiate.

Life history

The football fish was first discovered in the early 1900s by deep sea fisherman in search of flounder. Their poor musculature and cumbersome morphology indicate that female footballfish at least are probably poor swimmers and largely sedentary, lie-in-wait predators. They are primarily mesopelagic

Mesopelagic

The mesopelagic is that part of the pelagic zone that extends from a depth of 200 to 1000 metres below the ocean surface. It lies between the photic epipelagic above and the aphotic bathypelagic below, where there is no light at all...

, living in open water, with very few caught below 1,000 m (3,280 ft). Females are carnivorous

Carnivore

A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...

 and feed upon other pelagic fish

Pelagic fish

Pelagic fish live near the surface or in the water column of coastal, ocean and lake waters, but not on the bottom of the sea or the lake. They can be contrasted with demersal fish, which do live on or near the bottom, and reef fish which are associated with coral reefs.The marine pelagic...

 (such as lanternfish

Lanternfish

Cooper Lanternfishes are small mesopelagic fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represented by 246 species in 33 genera, and are found in oceans worldwide. They are aptly named after their conspicuous use of bioluminescence...

es and ridgehead

Ridgehead

Ridgeheads, also known as bigscales, are a family of small, deep-sea stephanoberyciform fish. The family contains approximately 37 species in five genera; their distribution is worldwide, but ridgeheads are absent from the Arctic Ocean and Mediterranean Sea...

s) and cephalopod

Cephalopod

A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...

s, as well as shrimp

Shrimp

Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

 and euphausiids that are presumably attracted to within striking distance by the footballfish' luminous lure.

Upon maturity, the tiny males of most species metamorphose into a parasitic form, which lacks both a lure and true teeth and is presumed not to feed. The parasitic males use their enlarged olfactory bulb

Olfactory bulb

The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...

s (as indicated by their enlarged nostrils) and sensitive eyes to home in on the pheromone

Pheromone

A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...

s and possibly the species-specific lures of mature females, as is the case in other ceratioid anglerfish families. With the exception of a few species — e.g., the Atlantic footballfish, Himantolophus groenlandicus, whose males are entirely free-living — the metamorphosed males attach themselves to the body of the female using their denticular hooks; the male's tissues then begin to coalesce with the female's, and the former's gonad

Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon and egg cells are gametes...

s begin to develop while all other organs degenerate. The male thus becomes inseparable from the female, deriving nourishment directly from her blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

.

Footballfish are presumed to be non-guarders and to spawn

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 pelagically. Their larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e are epipelagic (occurring in the well-lit 200 m of the water column), indicating they probably undergo an ontogenetic

Ontogeny

Ontogeny is the origin and the development of an organism – for example: from the fertilized egg to mature form. It covers in essence, the study of an organism's lifespan...

 descent into deeper waters as the larvae mature. Predators of footballfish include Sperm Whale

Sperm Whale

The sperm whale, Physeter macrocephalus, is a marine mammal species, order Cetacea, a toothed whale having the largest brain of any animal. The name comes from the milky-white waxy substance, spermaceti, found in the animal's head. The sperm whale is the only living member of genus Physeter...

s and other footballfish.

Humans do not use the fish, but scientists are attempting to use the shape of the fish to advance deep sea exploration.

Species

• Himantolophus albinares Maul, 1961
• Prickly anglerfish
  Prickly anglerfish
  The prickly anglerfish, Himantolophus appelii, is a footballfish of the family Himantolophidae, found around the world in the southern oceans , in deep water. Its length is up to 40 cm . It is a mesopelagic species....
  
  , Himantolophus appelii (Clarke, 1878)
• Himantolophus azurlucens Beebe & Crane, 1947
• Himantolophus borealis Kharin, 1984
• Himantolophus brevirostris (Regan, 1925)
• Himantolophus compressus (Osório, 1912)
• Himantolophus cornifer Bertelsen & Krefft, 1988
• Himantolophus crinitus Bertelsen & Krefft, 1988
• Himantolophus danae Regan & Trewavas, 1932
• Atlantic footballfish, Himantolophus groenlandicus Reinhardt, 1837
• Himantolophus litoceras Stewart & Pietsch, 2010
• Himantolophus macroceras Bertelsen & Krefft, 1988
• Himantolophus macroceratoides Bertelsen & Krefft, 1988
• Himantolophus mauli Bertelsen & Krefft, 1988
• Himantolophus melanolophus Bertelsen & Krefft, 1988
• Himantolophus multifurcatus Bertelsen & Krefft, 1988
• Himantolophus nigricornis Bertelsen & Krefft, 1988
• Himantolophus paucifilosus Bertelsen & Krefft, 1988
• Himantolophus pseudalbinares Bertelsen & Krefft, 1988
• Pacific footballfish, Himantolophus sagamius (Tanaka, 1918)