Ophichthidae
equatorial eel
Apterichtus equatorialis
FISH SPECIES
Long-bodied Fish
Explore fish with elongated, anguilliform or ribbon-like silhouettes, and learn how length changes locomotion and foraging.
FISH ATLAS / FIELD GUIDELong Bodied FishIN THIS CHAPTER01 / Characteristics02 / Lifestyle03 / Species04 / Field notes
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01 / NATURAL HISTORY
Characteristics
Elongated body plans reduce hydrodynamic drag, allow passage through tight apertures, and feature reduced or absent pelvic fins combined with extensive multi-vertebral muscular flexing systems.
- 01Anguilliform wave propulsion
- 02Crevice & conduit navigation
- 03Reduced appendages & low drag
02 / LIFESTYLE
Lifestyle
True eels swim via full-body anguilliform waves, sending lateral bends down their entire length to push against water, allowing them to reverse direction inside narrow subterranean burrows. Needlefish and pikes maintain a rigid elongated torso, keeping the body straight until their posterior fins and muscular caudal peduncle unleash sudden, explosive forward lunges.
OBSERVATION INDEX
- Full-body anguilliform undulation
- Reverse movement inside burrows
- Rigid body ambush alignment
03 / SPECIES
Representative species
Discover representative species illustrating the ecological diversity, morphologies and adaptations of this group.
equatorial eel
Pseudochromidae
Erdmann’s Dottyback
Pseudochromis erdmanni
Gobiidae
Erdmann’s dwarfgoby
Eviota erdmanni
Gobiidae
erect goby
Microgobius erectus
Gobiidae
Erythrops goby
Bryaninops erythrops
Gobiidae
Estuarine Frillfin
Bathygobius andrei
Atherinidae
Estuarine hardyhead
Craterocephalus honoriae
Ariidae
estuarine sea catfish
Cathorops aguadulce
Tripterygiidae
Estuarine triplefin
Forsterygion nigripenne
Sillaginidae
Estuarine whiting
Sillago vincenti
Plotosidae
Estuary cobbler
Cnidoglanis macrocephalus
Osmeridae
eulachon
Thaleichthys pacificus
Salmonidae
Euphrates trout
Salmo euphrataeus
Anguillidae
European eel
Anguilla anguilla
Ophichthidae
European finless eel
Apterichtus caecus
Elassomatidae
Everglades pygmy sunfish
Elassoma evergladei
Congridae
Evermann's conger
Congrosoma evermanni
Myctophidae
Evermann's lantern fish
Symbolophorus evermanni
Ophichthidae
Evermann's snake eel
Ophichthus lithinus
Adrianichthyidae
Evers' ricefish
Oryzias eversi
Cyprinidae
Evrotas minnow
Pelasgus laconicus
Blenniidae
Ewa blenny
Plagiotremus ewaensis
Stomiidae
Exotic snaggletooth
Eupogonesthes xenicus
Blenniidae
Eye-spot blenny
Ecsenius ops
04 / FIELD NOTES
A closer look
Why do eels and morays lack pelvic fins?
Pelvic fins create hydrodynamic drag and easily catch on obstructions when navigating tight crevices, burrows and rock cracks. Over evolutionary time, appendages were reduced or lost in favor of continuous median fins.
How do elongated fish like gar and needlefish hunt?
Rather than undulate their whole bodies, they hold their long torsos completely straight to resemble floating sticks or debris, then unleash rapid lateral head snaps or tail bursts to impale unsuspecting prey on their toothed jaws.