NOTACANTHIFORM CHARACTERISTICS:

      1) tail elongate, tapering posteriorly to a point; caudal fin absent

      2) mouth small, inferior, not extending past eye

      3) pelvic fins abdominal, connected along ventral midline with a membrane

      4) maxilla toothed, in gape, with a posteriorly directed spine

      5) base of anal fin extremely long

      ILLUSTRATED SPECIMENS:

      A) Notacanthus chemnitzii, SIO 87–84, 385 mm TL (Notacanthidae—spiny eels)

      B) Aldrovandia phalacra, SIO 68–463, 189.5 mm TL (Halosauridae—halosaurs; tail broken)

      ANGUILLIFORMES—Eels

      Historically, the true eels have been called the Apodes because they lack pelvic fins and a pelvic girdle. The pectoral fins and caudal fin may be present or absent. Scales are absent in most eels, but if present they are cycloid and imbedded. The gill openings of eels are narrow and gill rakers are absent. Eel leptocephali have a rounded caudal fin that is contiguous with the dorsal and anal fins. The Anguilliformes includes 15 families, 141 genera, and nearly 800 species. They are found in all major aquatic habitats of the world. Protoanguilla palau, recently described from deep reefs of Palau, represents a new genus and unique family of eels, the Protoanguillidae, that is hypothesized to be the sister group of all other eels (Johnson et al., 2012).

      REFERENCES: Böhlke, 1989; Johnson et al., 2012; Robins, 1989; Santini, Kong et al., 2013.

      ANGUILLIFORMES : ANGUILLIDAE—Freshwater Eels

      DIVERSITY: 1 genus, 18 species

      REPRESENTATIVE GENUS: Anguilla

      DISTRIBUTION: Atlantic, Indian, and Pacific oceans, and all continents except Antarctica

      HABITAT: Marine and freshwater; tropical to temperate; catadromous; demersal to benthic in lakes, rivers, and estuaries, benthopelagic in open ocean

      REMARKS: Though referred to as freshwater eels, the species in the Anguillidae are generally catadromous. While they live most of their adult lives in freshwater, they spawn in open ocean, far from land (Tsukamoto et al., 2011). Freshwater eels are also semelparous, meaning they die soon after spawning. Recent studies have shown that they are related to a group of deep-sea marine eels, the Nemichthyidae and Serrivomeridae (Inoue et al., 2010). Anguillids are generalized predators and feed on other fishes and benthic invertebrates. Freshwater eels are commercially important food fishes and several species support a large aquaculture enterprise.

      REFERENCES: Inoue et al., 2010; Smith, 1989; Tesch, 1977; Tsukamoto et al., 2011.

      ANGUILLID CHARACTERISTICS:

      1) lower jaw projecting beyond upper jaw

      2) pectoral fins well developed

      3) scales small, embedded in skin

      4) teeth small, in bands

      5) trunk lateral-line canal complete

      ILLUSTRATED SPECIMEN:

      Anguilla japonica, SIO 85–138, 356 mm TL

      ANGUILLIFORMES : MURAENIDAE—Moray Eels

      DIVERSITY: 15 genera, 198 species

      REPRESENTATIVE GENERA: Echidna, Gymnothorax, Muraena, Uropterygius

      DISTRIBUTION: Atlantic, Indian, and Pacific oceans

      HABITAT: Marine, occasionally freshwater; tropical to temperate; continental shelf to upper continental slope, benthic on or in coral and rocky reefs, as well as soft bottoms

      REMARKS: Unlike most eels, morays can be quite colorful with distinctive markings. They range in size from ∼20 cm to 3.75 m in total length, and are among the world’s largest eels. In addition to their laterally compressed head and body, morays have a characteristic raised-head profile behind the eyes. These eels are both predators and scavengers and eat living or recently dead fishes or crustaceans. Piscivorous species are characterized by long, needle-like teeth and highly mobile pharyngeal jaws (Mehta and Wainwright, 2008), while species specializing on crustaceans may have molariform teeth. Care should be taken when eating large morays as they are responsible for many cases of ciguatera poisoning. The phylogenetic relationships of morays were hypothesized by Tang and Fielitz (2013) based on molecular data.

      REFERENCES: Böhlke et al., 1989; Böhlke and McCosker, 2001; Böhlke and McCosker, in Carpenter and Niem, 1999; Mehta and Wainwright, 2008; Smith, 2012; Tang and Fielitz, 2013.

      

      MURAENID CHARACTERISTICS:

      1) pectoral fins absent

      2) posterior nostril high on head

      3) head and body laterally compressed for entire length

      4) gill opening reduced to small round hole or slit

      5) scales absent

      6) trunk lateral-line canal absent

      ILLUSTRATED SPECIMENS:

      A) Uropterygius versutus, SIO 59–7, 289 mm TL

      B) Gymnothorax moringa, SIO 71–275, 377 mm TL

      C) Enchelycore octaviana, SIO 65–33, radiograph

      ANGUILLIFORMES : OPHICHTHIDAE—Snake Eels and Worm Eels

      DIVERSITY: 52 genera, 318 species

      REPRESENTATIVE GENERA: Muraenichthys, Myrichthys, Ophichthus

      DISTRIBUTION: Atlantic, Indian, and Pacific oceans

      HABITAT: Marine, occasionally in freshwater; tropical to temperate; continental shelf to continental slope, usually benthic on or in soft bottoms, with some species occuring in midwaters of the mesopelagic

      REMARKS: The Ophichthidae is a large family of eels with considerable morphological diversity. For example, the pectoral, dorsal, anal, and caudal fins can be either present or absent, and the origin of the dorsal fin, when present, can be over the pectoral fin or well posterior. The unusual basket-like structure formed by the branchiostegal rays often involves rays that are detached from any other bone. Some species in the Ophichthinae use their hard, pointed tails to burrow backward, and their burrowing lifestyle implies that the bulk of their diet is likely benthic invertebrates. They are abundant in certain areas, caught by hook-and-line, and occasionally consumed by humans.

      REFERENCES: Böhlke and McCosker, in Carpenter and Niem, 1999; McCosker, 1977, 2010; McCosker et al., 1989; McCosker and Rosenblatt, 1998.

      

      OPHICHTHID CHARACTERISTICS:

      1) posterior (excurrent) nostril on upper lip (usually) or inside mouth

      2) tail usually hard, pointed; caudal fin absent in most species (present in Myrophinae)

      3) branchiostegal rays numerous (15–49), overlapping at ventral midline to form a basket

      4) scales absent

      5) trunk lateral-line canal complete, left and right sides connected by a canal across nape

      ILLUSTRATED SPECIMENS:

      A) Callechelys eristigma, SIO 65–263, 503 mm TL, holotype

      B) Scolecenchelys

---

Скачать книгу