Fishes: A Guide to Their Diversity. Philip A. Hastings
GENERA: Conger, Heteroconger, Paraconger
DISTRIBUTION: Atlantic, Indian, and Pacific oceans
HABITAT: Marine; tropical to temperate; continental shelf to abyssal plain, benthic on soft bottoms, often burrowing into substrates
REMARKS: Like the Ophichthidae, the Congridae is a speciose family exhibiting significant morphological and ecological variation, and is difficult to characterize. Conger eels generally have well-developed pectoral fins and large eyes for use in visual predation, but there are exceptions to both traits. They live in association with the benthos and range from depths of less than 5 m to more than 2,000 m. Most species actively feed on small fishes and invertebrates at night, but the Heterocongrinae form vast “gardens” in sands adjacent to reefs and are visual plankton pickers. Conger eels are important in the fish leather industry (Grey et al., 2006).
REFERENCES: Castle and Randall, 1999; Grey et al., 2006; Smith, 1989b; Smith, in Fischer et al., 1995.
CONGRID CHARACTERISTICS:
1) dorsal-fin origin over or just posterior to pectoral-fin insertion
2) posterior nostril just anterior to eye
3) pectoral fins usually present and well-developed (except in the Heterocongrinae)
4) scales absent
5) eight to twenty-two branchiostegal rays
6) trunk lateral-line canal complete
ILLUSTRATED SPECIMENS:
A) Ariosoma gilberti, SIO 69–235, 165 mm TL (Congrinae)
B) Heteroconger canabus, SIO 61–261, 760 mm TL, holotype (Heterocongrinae—garden eels)
ANGUILLIFORM DIVERSITY:
A) NEMICHTHYIDAE—snipe eels: Nemichthys scolopaceus, SIO 88–55, 706 mm TL
B) COLOCONGRIDAE—shorttail eels: Thalassenchelys foliaceus, SIO 70–333, 228 mm TL, leptocephalus larva
SACCOPHARYNGIFORMES—Swallowers and Gulper Eels
DIVERSITY: 4 families, 5 genera, 28 species
REPRESENTATIVE GENERA: Cyema, Eurypharynx, Monognathus, Neocyema, Saccopharynx
DISTRIBUTION: Atlantic, Indian, and Pacific oceans
HABITAT: Marine; tropical to temperate; midwater, lower mesopelagic to bathypelagic
REMARKS: The deep-sea swallowers and gulper eels are among the most distinctive and bizarre fishes, considered by some (e.g., Nelson, 2006) to be among the most morphologically modified vertebrates. With their huge mouths and highly distensible pharynx, they are clearly adapted for capturing and ingesting large prey items in the food-poor environment of the deep sea. In addition to the features listed below, they lack opercular bones and ribs, and have long, posterior extensions of both jaws. Swallowers and gulpers feed primarily on other fishes, and can swallow items at least as large as their body size. The tail of the swallowers ends in a luminous organ that might be used to attract prey.
REFERENCES: Nelson, 2006; Nielsen et al., 1989; Tighe and Nielsen, 2000.
SACCOPHARYNGIFORM CHARACTERISTICS:
1) mouth greatly enlarged
2) tail extremely elongate, caudal fin absent
3) abdominal portion of body much deeper than tail
4) body quite flaccid
5) scales absent
6) branchiostegal rays absent
ILLUSTRATED SPECIMENS:
A) Saccopharynx lavenbergi, SIO 75–272, 602 mm TL (Saccopharyngidae—swallowers)
B) Eurypharynx pelecanoides, SIO 72–180, 430 mm TL (Eurypharyngidae—pelican eels)
OTOCEPHALA
This group, called the Otomorpha by Wiley and Johnson (2010), includes the herrings and anchovies (Clupeiformes) and their sister group, the Ostariophysi (Arriata, 1999). Its members share several osteological features of the skull, vertebral column, and caudal fin, as well as a unique silvery area associated with the gas bladder (Lecointre and Nelson, 1996; Wiley and Johnson, 2010).
CLUPEIFORMES—Herrings, Anchovies, and Relatives
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