# Red-lipped batfish

The red-lipped batfish or Galápagos batfish (Ogcocephalus darwini) is a fish of unusual morphology found around the Galápagos Islands and off Peru at depths of 3 to 76 m (10 to 249 ft) . Red-lipped batfish are closely related to rosy-lipped batfish (Ogcocephalus porrectus), which are found near Cocos Island off the Pacific coast of Costa Rica. This fish is mainly known for its bright red lips. Batfish are not good swimmers; they use their highly adapted pectoral, pelvic and anal fins to "walk" on the ocean floor. When the batfish reaches maturity, its dorsal fin becomes a single spine-like projection (thought to function primarily as a lure for prey).

## Taxonomy

The red-lipped batfish was first formally described in 1958 by the American ichthyologist Carl Leavitt Hubbs with its type locality given as Tagus Cove on Isabela Island (Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard, 2024). The genus Ogcocephalus is classified within the "Eastern Pacific/Western Atlantic clade" of the family Ogcocephalidae (Derouen, Ludt, Ho, Chakrabarty, 2015). The family Ogcocephalidae is classified in the monotypic suborder Ogcocephaloidei within the order Lophiiformes, the anglerfishes in the 5th edition of Fishes of the World (Nelson, Grande, Wilson, 2016)

## Etymology

The redlipped batfish is a member of the genus Ogcocephalus, the name of which is a combination of ogkos, which means "hook", and cephalus, meaning "head", an allusion to the pointed rostrum on the snout of the type species. The specific name Charles Darwin to mark the centenary of the publication of On the Origin of Species and to recognise the importance that the observations made on the Galápagos Islands had in developing the theory of island endemism (Scharpf, 2024).

## Description

The red-lipped batfish reaches up to 40 centimetres (16 in) in length (Froese, Rainer; Pauly, Daniel 2016). Its body color is light brown and a greyish colour on its back (though not very visible in sea), with white countershading on the underside. On the top side of the batfish, there is usually a dark brown stripe starting at the head and going down the back to the tail. The snout and horn of the red-lipped batfish is a brownish color. As the name of the fish states, the batfish has bright, almost fluorescent, red lips. The color of the squamation of the red-lipped batfish is shagreen-like with a relatively smooth texture. The bucklers are concealed by a layer of fine spinules.
When compared to the O. porrectus, the red-lipped batfish has a shorter disk perimeter but a higher fibre pectoral fin ray count. Regarding the number of scales along the lateral line, there are four to nine subopercular scales, six to nine on the cheek, usually. The red-lipped batfish has around 19-20 vertebrae (Froese, Rainer; Pauly, Daniel 2016).
Red-lipped batfish have extremely bright red lips which allows people to distinguish them from other batfish. Marine biologists hypothesize that the bright red lips may enhance species recognition during spawning.
Their large, laterally placed eyes provide a wide field of vision, allowing them to detect prey and predators effectively. Positioned on top of their flat heads, the eyes help the fish remain hidden while observing their surroundings from the seabed (Hubbs, Carl L., 1958).
Although the fish's bright red lips attract attention, it can camouflage itself by changing its body color to blend with the sand or rocks on the ocean floor. This adaptation helps it ambush prey and evade predators (Hubbs, Carl L., 1958).

## Diet and feeding strategies

Red-lipped batfish are piscivores/invertivores and tend to be more active at night (Hubbs, Carl L., 1958), mainly feeding on other small fish and small invertebrates including shrimp, crabs, worms and mollusks found on the seafloor where the batfish feeds.
Specialized Sensory Detection: The presence of ampullae of Lorenzini, sensory organs that detect weak electrical fields, provides an edge when hunting in low-visibility waters (Chambers, Harry, 2023).
On the top of the batfish's head there is a special body part that extends outward called an illicium. After the red-lipped batfish fully matures, its dorsal fin becomes a single spine-like projection that comes out of the top of the head. The batfish uses the illicium as a way to lure prey near them.
At the top of its illicium is an esca. The esca emits a bright light and since these fish dwell in deep waters, the light lures other fish to where the batfish is positioned. The esca lures the prey to the batfish which then allows it to eat those small creatures which fall into its trap.
The red-lipped batfish uses suction feeding, a common mechanism in fish, which involves creating a rapid influx of water to pull prey into its mouth. This technique depends on expanding the buccal cavity, generating suction force to capture prey efficiently, even in benthic environments where mobility is limited. The fish's specialized jaw protrusion plays a role in enhancing this process by increasing the volume of water drawn into the mouth, improving the effectiveness of prey capture (Mark, 2005) (Timothy, 2007). Additionally, the batfish's suction feeding strategy aligns with observations across teleost fishes, which use this method to ambush and capture small, non-evasive prey such as shrimp and crabs. This adaptation is crucial, given the batfish's preference for walking along the ocean floor rather than swimming actively, which would typically hinder high-speed chases (Mark, 2005).

## Reproduction

Male red-lipped batfish engage in a distinctive courtship dance, swaying their bodies and shaking their heads to attract females. Once a female is interested, the pair participates in a ritual dance and mate (Buono, Emily, 2023). After mating, females lay sticky eggs that adhere to the ocean floor. Males are responsible for guarding the eggs, fanning them with their fins to maintain oxygen flow and protect them from predators until they hatch (Hubbs, Carl L., 1958).
These fish exhibit communicative behaviors within small groups through body movements. They wiggle or sway their fins, likely signaling territory claims or intentions during mating seasons. This physical communication ensures harmony and aids in social bonding within their habitat (Buono, Emily, 2023).

## Habitat

Red-lipped batfish can be found at depths of 3 to 76 m (10 to 249 ft) in the Pacific Ocean around the Galapagos Islands and off Peru (Froese, Rainer; Pauly, Daniel 2016). It has been noted before that a few specimens of red-lipped batfish were found in fishnets in California, but all these types of sightings are extremely rare, and could very well be another type of batfish. They are bottom dwellers, so they are usually found within the sand or ocean floor. Although they are considered shallow-water forms, they occasionally come to the surface over deep water (Hubbs, Carl L., 1958). They tend to associate themselves with the edges of reefs up to about 120 m deep (Froese, Rainer; Pauly, Daniel 2016).

## Adaptations and Unique Features

Walking Fins: The pectoral, pelvic, and anal fins have evolved to function like limbs, allowing the batfish to "walk" along the ocean floor. When moving, it tucks its fins and propels forward in a way similar to a frog's awkward gait, which enhances its ability to maneuver among rocky or sandy substrate (Chambers, Harry, 2023) (Hubbs, Carl L., 1958).
Besides its bright red lips, the batfish can also change the color of its skin to blend with the environment. This defense mechanism makes it almost invisible among coral reefs and helps avoid predators (Chambers, Harry, 2023).

## Predators and Threatens

The red-lipped batfish has no known direct threats. However, rising sea temperatures and coral bleaching could pose a threat, as it would alter the natural habitat and may cause a decline in the availability of a natural food source.
As bottom-dwellers, batfish are at higher risk of ingesting microplastics or becoming entangled in discarded fishing gear. Ongoing initiatives to reduce plastic pollution in the Galápagos marine ecosystem can indirectly benefit species like the red-lipped batfish (Jenny, 2016).