#ophidiiformes

Robust Assfish (Bassozetus robustus), family Ophidiidae, order Ophidiiformes, found in the deep ocean in tropical and temperate parts of the world

The faceless cusk has a face only a mother could love- because they really don't have much of a face at all! The only obvious external features these eels have are a pair of large nostrils. The mouth is obscured to most observers as it is located on the underside of the head, and the eyes are buried deep beneath the skin and don't do much more than sense changes in light.

(Image: A faceless cusk eel (Typhlonus nasus) by NOAA Office of Ocean Exploration and Research)

Bonus: Here's a video of a faceless eel in action:

CUSK-EEL SANCTUARY SPOTTED AT DEEP-SEA METHANE SEEP OFF CHILE

A recent expedition off the Chilean coast has revealed dozens of red cusk-eels (Genypterus chilensis), nestled within a dense grove of tube worms at a methane seep. This marks the first documentation of these commercial fish adopting a chemosynthetic ecosystem as their habitat. Intriguingly, high-definition video footage suggests the eels may be visiting this otherworldly landscape for a specific service: parasite removal by resident spider crabs, pointing toward a complex symbiotic relationship in the abyss.

This discovery fundamentally challenges our understanding of methane seeps. Rather than existing as isolated biological islands, these environments appear deeply connected to broader ocean systems, serving as potential hubs for species targeted by fishing fleets. The finding carries significant urgency, as the red cusk-eel is considered vulnerable to overfishing. The surrounding seafloor was littered with lost fishing gear, a silent testament to the fact that this newly studied scientific wonder may already be known to local fishermen, placing it directly in the path of human activity.

The implications for conservation and fishery management are profound. If these seeps function as essential cleaning stations or spawning grounds, their protection becomes critical for sustaining fish populations. Researchers emphasize this two-day glimpse represents just the beginning; the full ecological story throughout the seasons remains unknown. This discovery serves as a powerful reminder that the deep sea still holds profound mysteries, and its protection is inextricably linked to the health of the ocean resources upon which we depend.

Reference: Levin et al., 2025. Congregation of cusk‐eels (Genypterus chilensis, Ophidiiformes) at a deep‐sea methane seep off Chile. Ecology

(Sources - 1, 2, 3, 4)

Order: Ophidiiformes

Common Name: “cusk-eels” and “brotulas”

Families: 6 - Acanthonidae (“deepsea cusk-eels”), Brotulidae (“bearded cusk-eels”), Ophidiidae (“cusk-eels”), Carapidae (“pearlfishes”), Bythitidae (“viviparous brotulas), and Parabrotulidae (“false brotulas”)

Anatomy: long slender body; large snout; tadpole-like shape; either smooth scales or no scales; long dorsal fin and an anal fin that typically runs into the caudal fin

Diet: smaller fish, crustaceans

Habitat: both freshwater and marine habitats, including abyssal depths; mainly in the tropics and subtropics

Evolved in: Late Cretaceous

Propaganda under the cut:

Ogilbia cayorum

Key Brotula juv.

Image source

Status: Least concern

Ghostfish (Aphyonidae)