Overview

Brief Summary

Introduction

The order Lophiiformes contains a highly diverse array of marine fishes that are primitively benthic shallow-water dwellers, but have evolved to form several groups of deep-shelf and slope inhabitants as well as a highly modified assemblage of open-water, meso- and bathypelagic species. Commonly referred to as anglerfishes, the group is characterized most strikingly by the structure of the first dorsal-fin spine, typically placed out on the tip of the snout and modified to serve as a luring apparatus.

The order contains approximately 322 living species, distributed among 65 genera and 18 families. The families themselves are distributed among five suborders (Pietsch, 1984a; Pietsch and Grobecker, 1987): the Lophioidei (reviewed by Caruso, 1981, 1983; Caruso and Bullis, 1976), containing a single family, four genera, and 25 species of relatively shallow-water, dorso-ventrally flattened forms, commonly referred to as the goosefishes or monkfishes; the Antennarioidei, with four families, 15 genera, and about 54 species, nearly all laterally compressed, shallow- to moderately deep-water, benthic forms, with a host of common names including frogfishes, sea-mice, sea-toads, warty anglerfishes, and handfishes (Pietsch, 1981, 1984a, 1984b; Last et al., 1983); the Chaunacoidei or coffinfishes, two genera and perhaps as many as 14 species (Caruso, 1989a, 1989b) of more or less globose, deep-water benthic forms; the Ogcocephaloidei or batfishes, a single family of ten genera and some 67 species of dorsoventrally flattened, deep-water benthic forms (Bradbury, 1967, 1980, 1988, 1999); and the Ceratioidei, the deep-sea anglerfishes, containing 11 families, 35 genera, and 162 species (Bertelsen, 1951, 1984; Pietsch, 1984a, 1999).

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Comprehensive Description

Fossil Lophiiforms

Patterson and Rosen (1989: 23) summarized what little is known about fossil lophiiforms. The record extends back to the early Pliocene of Algeria (Lophius budegassa Arambourg), but better represented in the early Eocene of Monte Bolca (Eastman, 1904), where Blot (1980) said that a new genus of lophiid is to be named for Lophius brachysomus Agassiz; that a new genus of ogcocephalid is to be described; and that Histionotophorus bassanii (de Zigno) is an antennariid. Blot (1980) did not cite any reasons for placing Histionotophorus in the Antennariidae, and did not cite Rosen and Patterson's (1969) brief discussion of the genus, which they placed in the antennarioid family Brachionichthyidae. Pietsch (1981: 416) agreed, and suggested that the Eocene genus is synonymous with the extant Brachionichthys Bleeker. Thus the Monte Bolca lophiiforms indicate that at least three of the major lophiiform lineages (lophioids, antennarioids, and ogcocephaloids) were already in existence in the early Eocene. The only known ceratioid fossil, a female specimen identified as Acentrophryne longidens Regan (family Linophrynidae), was described from the Late Miocene of California by Pietsch and Lavenberg (1980).

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Relationship of Lophiiformes to Other Paracanthopterygii

The Lophiiformes has traditionally been allied with the order Batrachoidiformes. Regan (1912) initially believed these two groups to be so closely related that he included them as suborders of an order he called the "Pediculati." At that time Regan (1912:278) wrote: "The Batrachoidea are here included in the Pediculati rather than in the Percomorphi, for it can hardly be the case that the resemblance in osteological characters, especially in the structure of the pectoral arch, is not due to real affinity." But later Regan (1926:3) separated the Lophiiformes from the Batrachoidiformes, stating that "although the resemblances in the pectoral arch may be due to relationship, the differences in other characters are sufficient to keep them apart."

Since that time, Regan's (1926) revised opinion has been almost universally accepted. The more significant studies that reach this conclusion being those of Regan and Trewavas (1932), Gregory (1933), Gregory and Conrad (1936), Gregory (1951), Eaton et al. (1954), and Monod (1960). Greenwood et al. (1966) and Rosen and Patterson (1969) also agreed, summarizing the available supporting evidence and proposing further a close phylogenetic relationship between these two orders and the Gobiesociformes, these three taxa forming a so-called "Batrachoidiform Lineage" of the Paracanthopterygii. Since the publication of these two papers, Gosline (1970), in a long and detailed paper, removed the order Gobiesociformes from this lineage (and from the Paracanthopterygii), and recognized it, together with the Callionymidae and Draconettidae, as an order of perciform derivation. Without comment or new evidence, Lauder and Liem (1983) reversed Gosline's (1970) decision by reconstituting the "Batrachoidiform Lineage" as originally proposed by Rosen and Patterson (1969). Following Gosline (1970) in excluding the Gobiesociformes, Patterson and Rosen (1989: 24) once again reviewed all the available evidence and identified several new and significant characters in the anterior vertebrae and gill-arch skeleton. Of the batrachoidiforms and lophiiforms, they concluded that "the latter are surely monophyletic, the former less so, but if so, the two are sister groups."

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Economic Importance

Aside from lophiids, which are highly esteemed as food-fishes and utilized fresh, frozen, or for fishmeal and oil, lophiiforms have limited economic value and are generally not considered an exploitable source of animal protein. Antennariids, and to a smaller extent ogcocephalids, are utilized by the aquarium trade. Ceratioids have occasionally been recorded as food items for predatory fishes (e.g., Thunnus, and the lancetfishes Aphanopus carbo and Alepisaurus ferox; Maul, 1961, 1962; Matthews et al., 1977) and whales (e.g., sperm whales, Physeter catodon; Clarke, 1950, 1956; Penrith, 1967) but they are not known to constitute the principal or preferred diet of any species.

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Characteristics

Anglerfishes display a wide range of body forms, from globose, almost spherical, to elongate, laterally compressed, or extremely dorsoventrally depressed. The head and mouth are typically large, the premaxillae protractile. The teeth in the jaws are numerous, small, villiform, in several rows, or very few in number and developed to form large fangs (as in most Ceratioidei). Vomerine teeth are usually present (absent in some Ceratioidei); palatine teeth are present or absent. The eyes are typically large (except in most adult female Ceratioidei). The anterior-most dorsal spine or illicium is nearly always present (but absent in male Ceratioidei and in both sexes of the ceratioid family Neoceratiidae), usually bearing a terminal bait or esca (absent in some Antennariidae, male Ceratioidei, and in both sexes of the ceratioid family Neoceratiidae). The esca is simple to highly complex, bioluminescent in nearly all female Ceratioidei. The bony support for the illicium (illicial pterygiophore), which lies within a shallow trough on the anterodorsal surface of the cranium, is highly protrusible in some taxa. The pectoral fins are highly modified, leg-like (except in Ceratioidei). When present, the pelvic fins are jugular in position and consist of 1 spine and 4 or 5 rays (pelvics are absent in Ceratioidei, except for larval Caulophrynidae). The gill openings are restricted to a small, elongate, tube-like opening situated immediately dorsal to, posterior to, or ventral to (rarely partly anterior to) the base of the pectoral fin. A pseudobranch is present or absent. A swimbladder is usually absent (present and physoclistous in some Antennariidae). The eggs are spawned in a double, scroll-shaped mucous sheath. The soft dorsal fin consists of 3-22 rays, the anal fin 3-19 rays, the pectoral fin 4-30 rays, and the caudal fin 8-10 rays.

The coloration of anglerfishes ranges from uniform gray, brown to black, without markings of any kind (e.g., some Lophioidei and Ceratioidei), to multicolored and complexly patterned (e.g., Antennariidae).

Typically small fishes, the largest known individuals of most families attain standard lengths of approximately 100-250 mm, but some (e.g., Lophiidae, some Antennariidae, Himantolophidae, Thaumatichthyidae, Ceratiidae, and Gigantactinidae) become much larger, lophiids exceeding a meter in length and a weight of 27 kg. Ceratioids display an extreme sexual dimorphism in which males are dwarfed, the largest known free-living individuals of most families measuring 10-30 mm SL (standard length), but reaching 40 mm SL in Himantolophidae; parasitically attached individuals usually range from about 7-30 mm SL, but reach nearly 120 mm SL in Ceratiidae.

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Distribution

Geographic Distribution

With the exception of a single species of Antennariidae occasionally taken in brackish or even fresh water (Antennarius biocellatus; see Pietsch and Grobecker, 1987: 174), lophiiforms are strictly marine fishes distributed throughout all oceans and major seas of the world. Only the Lophiidae, however, are present in the Mediterranean. Most are benthic as adults, typically occupying depths that range from the surface down to approximately 200 m, a few species extending down to 2500 m or more. All Ceratioidei (with the exception of the thaumatichthyid genus Thaumatichthys, which is benthic in 1000-3600 m) are meso- and bathypelagic, concentrated between approximately 800 and 2500 m.

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Physical Description

Morphology

List of Synapomorphies

  1. Spinous dorsal fin primitively of six spines, the anteriormost three of which are cephalic in position and modified to serve as a luring apparatus
  2. Epiotics separated from parietals and meeting on the midline posterior to the supraoccipital
  3. Gill opening restricted to a small, elongate, tube-like opening adjacent to pectoral-fin base
  4. A single hypural plate emanating from a single complex half-centrum
  5. Ventralmost pectoral radial considerably expanded distally
  6. Eggs spawned in a double scroll-shaped mucous sheath
  7. Posteromedial process of vomer emerging from ventral surface as a laterally compressed, keel-like structure
  8. Postmaxillary process of premaxilla spatulate
  9. Opercle reduced
  10. Ectopterygoid triradiate
  11. Proximal end of hypobranchials II and III bifurcate
  12. Interhyal with a medial, posterolaterally directed process
  13. Illicial pterygiophore and pterygiophore of third dorsal spine with highly compressed, blade-like dorsal expansions
  14. Eggs and larvae small
  15. Head of larvae large relative to body
  16. Number of dorsal-fin spines reduced
  17. Loss of pharyngobranchial IV
  18. Second dorsal spine reduced and embedded beneath skin of head
  19. Gill filaments of gill arch I absent
  20. Second dorsal spine reduced to a small remnant
  21. Third dorsal spine and pterygiophore absent
  22. Epibranchial I simple, without ligamentous connection to epibranchial II
  23. Posttemporal fused to cranium.

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Life History and Behavior

Life Cycle

Reproduction and Early Life History

Little is known about the reproduction and early life history of lophiiform fishes (Breder and Rosen, 1966; Pietsch, 1976, 1984a; Martin and Drewry, 1978; Pietsch and Grobecker, 1987), detailed information being available for only a few members of the Lophiidae, Antennariidae, and most ceratioid families. Scattered bits of published data are also available for the Tetrabrachiidae, Brachionichthyidae, Chaunacidae, and Ogcocephalidae, but nothing has been reported for the Lophichthyidae.

Observations of courtship and spawning behavior have been reported for only a few antennariids. Eggs and larvae have been adequately described for two of the 25 known species of Lophiidae; larvae, but not eggs, have been described in a third species. Within the Antennariidae, unequal information concerning early life-history stages is available for only four of the 42 recognized species. For the Tetrabrachiidae and Brachionichthyidae, all that is published is a mention of egg attachment to dorsal-fin rays and substrate, respectively (Pietsch and Grobecker, 1980). For chaunacids and ogcocephalids, aside from brief descriptions of ovarian structure, limited (by available material) developmental series of an unidentified species of each of two genera (Chaunax and Ogcocephalus) were described by Pietsch (1984a). Finally, larvae, but not eggs, have been adequately described for most families of the Ceratioidei. For a full summary, see Pietsch (1984a), Pietsch and Grobecker (1987), and numerous references cited therein.

Probably the most striking characteristic of early ontogeny in lophiiform fishes is that eggs are spawned encapsulated within a non-adhesive, balloon-shaped mucoid mass (Ray, 1961) or, more typically, a continuous, ribbon-like sheath of gelatinous mucous, often referred to as an "egg-raft" or "veil" (with some exceptions, see Pietsch and Grobecker, 1980, 1987). These egg-rafts are complex structures of positive bouyancy that float freely at the surface. Each is a product of two confluent ovaries within which each individual egg floats in a separate chamber provided with openings for the circulation of water (Rasquin, 1958; Martin and Drewry, 1978, and numerous references cited therein). This peculiar structure, differing considerably from any other ovarian product known in fishes (Breder and Rosen, 1966), is an excellent device for broadcasting a large number of small eggs over great geographic distances providing for development in relatively productive surface waters (Gudger, 1905; Pietsch and Grobecker, 1980, 1987).

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Evolution and Systematics

Evolution

Discussion of Phylogenetic Relationships

View Lophiiformes Tree

The relationships of the Lophiiformes as presented by Pietsch and Grobecker (1987). For character states, click here: 1-6, 7-9, 10-11, 12-13, 14-17, 18-19, and 20-23.


That the order Lophiiformes constitutes a natural assemblage seems certain. All included taxa share at least six unique and morphologically complex synapomorphic features (numbered 1 through 6 in the cladogram; a modification of Pietsch, 1981, 1984a):

  1. Spinous dorsal fin primitively of six spines, the anterior-most three of which are cephalic in position, the first modified to serve as a luring apparatus (involving numerous associated specializations, e.g., a medial depression of the anterior portion of the cranium, loss of the nasal bones and supraoccipital lateral-line commissure, and complex modifications of associated musculature and innervation);
  2. Epiotics separated from the parietals and meeting on the midline posterior to the supraoccipital;
  3. Gill opening restricted to a small, elongate, tube-like opening situated immediately dorsal to, posterior to, or ventral to (rarely partly anterior to) the pectoral-fin base;
  4. A single hypural plate emanating from a single complex half-centrum;
  5. Ventralmost pectoral radial considerably expanded distally (Pietsch, 1981: 397, 411, figs. 14, 40); and
  6. Eggs spawned in a double, scroll-shaped mucous sheath (Rasquin, 1958; Pietsch and Grobecker, 1987: 351).

Since Regan (1912), three major lophiiform taxa of equal rank have been recognized by nearly all authors. These taxa, together with their currently recognized families (the 11 families of the meso- and bathypelagic Ceratioidei excluded; see Bertelsen, 1951: 29; and Pietsch, 1972: 18), are as follows:

  • Suborder Lophioidei
    • Family Lophiidae
  • Suborder Antennarioidei
    • Family Antennariidae
    • Family Tetrabrachiidae
    • Family Lophichthyidae
    • Family Brachionichthyidae
    • Family Chaunacidae
    • Family Ogcocephalidae
  • Suborder Ceratioidei

Pietsch (1981: 416, fig. 41) attempted to test the validity of Regan's (1912) concept of three major lophiiform taxa by using cladistic analysis. In that study, serious difficulty was encountered in efforts to establish monophyly for the six families of Regan's (1912) Antennarioidei. Although a number of synapomorphic features were found to support a sister-group relationship between the four families Antennariidae through Brachionichthyidae, and between the families Chaunacidae and Ogcocephalidae, no convincing synapomorphy was found to link these two larger subgroups.

In a more recent attempt, Pietsch and Grobecker (1987: 268, fig. 110) proposed a new cladogram, which, in resolving the former difficulties, differed significantly from that previously published (Pietsch, 1981, fig. 41). In this revised cladogram, the suborder Antennarioidei is restricted to just four families: the Antennariidae, recognized as the sister-group of the Tetrabrachiidae, these two families together forming the sister-group of the Lophichthyidae, and this assemblage of three families forming the sister-group of the Brachionichthyidae. These relationships are supported by a total of seven synapomorphies, most of which were previously described by Pietsch (1981):

  1. Posteromedial process of the vomer emerging from the ventral surface as a laterally compressed, keel-like structure, its ventral margin (as seen in lateral view) strongly convex (1981: 397, figs. 4-6);
  2. Postmaxillary process of the premaxilla spatulate (1981: 398, figs. 8, 20);
  3. Opercle similarly reduced in size (1981: 401, figs. 9, 21);
  4. Ectopterygoid triradiate, a dorsal process overlapping the medial surface of the metapterygoid (1981: 400, figs. 9, 21, 22);
  5. Proximal end of hypobranchials II and III deeply bifurcate (1981: 407, figs. 11, 28, 29);
  6. Interhyal with a medial, posterolaterally directed process that makes contact with the respective preopercle (1981: 400, fig. 26);
  7. Illicial pterygiophore and pterygiophore of the third dorsal spine with highly compressed, blade-like dorsal expansions (1981: 410, figs. 36, 37).

The present interpretation of lophiiform relationships differs further from any previously proposed hypothesis in considering the Antennarioidei (sensu stricto) to form the primitive sister-group of a much larger group that includes the Chaunacoidei, the Ogcocephaloidei, and the Ceratioidei. The Ogcocephaloidei are in turn recognized as the primitive sister-group of the Ceratioidei.

Monophyly for a group containing the suborders Antennarioidei, Chaunacoidei, Ogcocephaloidei, and Ceratioidei is supported by four synapomorphies, all previously identified by Pietsch (1984a):

  1. Eggs and larvae small (at all stages the eggs are considerably less than 50% the diameter of those of lophioids; the smallest larvae are certainly less than 50%, and probably less than 30%, the size of those of lophioids; size at transformation to the prejuvenile stage is less than 60% that of lophioids; Pietsch, 1984a, fig. 164);
  2. Head of larvae proportionately large relative to the body (always greater than 45% SL, compared to less than 30% in lophioids; Pietsch, 1984a, fig. 164);
  3. Number of dorsal-fin spines reduced from a primitive six in lophioids to three or less (Pietsch, 1981: 409, figs. 36-38);
  4. Pharyngobranchial IV absent (present and well toothed in lophioids; Pietsch, 1981: 401, figs. 11, 28-32).

Monophyly for a group containing the suborders Chaunacoidei, Ogcocephaloidei, and Ceratioidei is supported by two synapomorphies:

  1. Second dorsal-fin spine reduced and embedded beneath skin of the head (Pietsch, 1981: 410, figs. 36-38);
  2. Gill filaments of gill arch I absent (but present on proximal end of ceratobranchial I of some ceratioids; Bradbury, 1967: 408; Pietsch, 1981: 415).

Monophyly for a group containing the Ogcocephaloidei and Ceratioidei is supported by four synapomorphies:

  1. Second dorsal-fin spine reduced to a small remnant (well developed in all other lophiiforms and secondarily developed in the ceratioid families Diceratiidae and Ceratiidae; Bertelsen, 1951: 17; Pietsch, 1981: 410, fig. 38);
  2. Third dorsal-fin spine and pterygiophore absent (present in all other lophiiforms; Bertelsen, 1951: 17; Bradbury, 1967: 401; Pietsch, 1981: 410, fig. 38);
  3. Epibranchial I simple, without ligamentous connection to epibranchial II (in batrachoidiforms and all other lophiiforms, epibranchial I bears a medial process ligamentously attached to the proximal tip of epibranchial II; Pietsch, 1981: 401, figs. 28-32);
  4. Posttemporal fused to cranium (attached to the cranium in batrachoidiforms and all other lophiiforms in such a way that considerable movement in an anterodorsal-posteroventral plane is possible; Pietsch, 1981: 411).

Of the possible cladograms that could be constructed on the basis of the data provided, the hypothesis presented is by far the most parsimonious (but see Pietsch, 1984a: 324, for a discussion of convergence or reversal of character states).

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Functional Adaptations

Functional adaptation

Lure attracts prey: anglerfish
 

The rod-like lure on the head of a female anglerfish attracts prey using bioluminescence.

       
  "The female anglerfish is squat and lumpy in shape, equipped with many needle-sharp teeth in her huge mouth, and a small luminous lure like a fishing-rod (hence her name) by which she attracts prey fish within reach of her jaws." (Foy and Oxford Scientific Films 1982:52)
  Learn more about this functional adaptation.
  • Foy, Sally; Oxford Scientific Films. 1982. The Grand Design: Form and Colour in Animals. Lingfield, Surrey, U.K.: BLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, London. 238 p.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
                                        
Specimen Records:1,156Public Records:649
Specimens with Sequences:950Public Species:103
Specimens with Barcodes:933Public BINs:138
Species:187         
Species With Barcodes:168         
          
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Barcode data

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Source: Barcode of Life Data Systems (BOLD)

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Locations of barcode samples

Collection Sites: world map showing specimen collection locations for Lophiiformes

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