Remora, also known as suckerfish, are a family of ray-finned fish in the order Perciformes. Remoras use a modified dorsal fin located on top of their heads to attach themselves to larger marine animals such as sharks, mantas, whales, and turtles. There are eight species in the remora family and they are found in warm and temperate oceans around the world.
What are remoras?
Remoras, often called suckerfish or shark suckers, are elongated fish with oval-shaped bodies that can grow up to 3 feet long. Their most distinctive feature is their dorsal fin that has evolved into a large, flat, oval-shaped suction disc on the top of their heads. The suction disc is made up of spiny lamellae (flat blades) arranged in rows that act like suction cups, allowing remoras to attach themselves to larger marine animals.
Remoras use their suction discs to form commensal relationships with host organisms. This means the remora benefits from the relationship while the host organism is not harmed. By latching onto sharks, whales, sea turtles and other large marine animals, remoras hitch free rides, gain transportation to new feeding grounds, and save energy from not having to swim constantly. They also feed on scraps of food dropped by their hosts.
There are eight species of remora distinguished by differences in their suction disc structure and body size:
- Common remora – Attaches mainly to sharks and grows up to 3 feet long
- Slender suckerfish – Prefers to cling to turtles and rays
- White suckerfish – The smallest species at only about 12 inches long
- Spearfish remora – Named for their narrow disc shape
- Whalesucker fish – Latches onto whales and porpoises
- Opah suckerfish – Found exclusively on opah fish
- Manta remora – Associates exclusively with manta rays
- Coelorinchus caelorhincus – The only species to live at depths below 3,000 feet
Where are remoras found?
Remoras live in tropical and temperate oceans around the world. They can be found in the Atlantic, Pacific, and Indian Oceans clinging to hosts in shallow reefs and open waters. Some species have been recorded at depths of up to 3,000 feet.
Remoras are commonly found around offshore oil rigs and floating debris where their host organisms tend to congregate. They are highly migratory and will travel long distances attached to whales, sea turtles, and oceanic whitetip sharks.
What do remoras eat?
Remoras are opportunistic eaters that primarily consume scraps of food dropped by their host organisms. Their diet consists of leftovers including crustaceans, small fish, squid, and octopus. Some species will also feed on feces and parasites on the skin of their hosts.
When detached from hosts, remoras are capable predators on their own. They will hunt small fish like sardines, anchovies, mackerel, and juvenile tuna. Their slender bodies allow them to dart quickly to catch prey.
How do remoras attach to their hosts?
A remora’s unique suction disc provides incredibly strong adhesive properties to latch onto hosts. It consists of lamellae (flat spiny blades) arranged in oblique rows that can be raised or lowered to increase or decrease suction. Muscles around the disc allow the remora to tilt the disc up or down to facilitate attachment and quick release.
When a remora encounters a potential host, it first positions itself perpendicular to the host’s body. It then presses the lips of its disc against the host’s surface while elevating the lamellae. This creates a strong negative pressure suction. The disc lip has inward facing spines that help grip the host.
Once attached, remoras can pivot their disc to maximize grip strength. But they are also able to release quickly when necessary. Using specialized muscles, remoras can instantly drop the lamellae to disengage the suction and swim free of the host.
Do remoras hurt their hosts?
Remoras form commensal relationships with their hosts, meaning they receive benefits from hitching rides while the host organisms are not harmed. They do not feed on their hosts like parasites would. The suction disc does not penetrate the host’s body or damage its skin.
However, large remoras could pose issues for marine mammals or sea turtles when attached in big numbers. Too many remoras piled onto one area creates drag that could impede the host’s ability to swim and catch food efficiently. Some green sea turtles and whales have been observed with over a dozen remoras latched onto them at once.
Are remoras edible?
Yes, remoras are edible fish that have been consumed by humans in certain cultures. However, remoras are not a mainstream food fish like tuna or salmon. There are a few reasons they have not gained widespread popularity as a table fish:
- Low meat yield – Remoras are extremely bony which leaves little edible flesh.
- Not abundant – They are not found in large aggregations like schooling fish.
- Difficult to catch – Their symbiotic relationships make them uncommon targets for fishermen.
But remoras have been eaten in isolated cases, usually opportunistically when they detach from their hosts. For example, spear fishermen who kill a large fish like a tuna will sometimes find remoras fall off and can be taken for food as well. There are also a few cultures that actively fish for remoras in small numbers to eat when other fish are unavailable.
How do you cook remora?
The traditional way to prepare remora is to cook it over an open fire or grill it. The flesh is lean with a flaky texture and mild flavor. When cooked thoroughly, remora meat has been described as slightly sweet tasting.
Since remoras have a high bone to flesh ratio, the meat is usually pickled off the bones then used in soups or stews. Sometimes the bones are charred and smashed to get every little bit of flesh. Fried remora has also been served in some Pacific island cultures.
What does remora taste like?
Those who have eaten remora say it has a mild, sweet flavor and firm, flaky texture when cooked. The taste has been compared to other mild white fish like halibut or cod. However, remora is extremely bony which limits the amount of edible meat. The small yield of flesh can dry out quickly so must be cooked carefully.
When pickled, remora meat takes on a tangy flavor. In soups and stews it becomes tender with a savory umami taste. Overall, remora is a bland fish that takes on the flavor of seasonings added to it. The meat readily absorbs smoky, salty and pickled flavors.
Is remora healthy to eat?
Remoras are not known to contain any toxins or inherent health hazards that would make them unsafe to eat. As bottom feeding carnivorous fish, remoras do bioaccumulate some mercury and other heavy metals in their tissues like most fish. But mercury levels are generally low to moderate, on par with many popular food fish. Remora meat is lean with lots of protein, minerals like selenium, vitamin B12, and heart healthy omega-3 fatty acids.
However, older, larger specimens may potentially carry higher mercury concentrations. To minimize this risk, smaller remoras should be targeted for harvest. The US FDA and EPA provide guidelines for limiting mercury exposure from seafood in weekly meal plans.
Basic safety precautions should be taken when preparing and eating any wild fish. Proper cooking and storage is necessary to prevent contamination or growth of bacteria that could cause illness.
Overall, eating remora infrequently should pose little health risk in most cases. But children and pregnant women may still want to avoid it due to vulnerability to mercury exposure.
Where is remora commercially fished?
Remora is rarely targeted by commercial fishing operations and there are no large scale remora fisheries. The difficulty of reliably catching remoras and the low yield of edible meat does not support remoras being fished commercially in most regions.
However, remoras may be opportunistically landed as bycatch when commercial fishing vessels harvest larger pelagic fish like tuna. Longline fishing boats will find remoras attached to mahi-mahi, wahoo, and other fish hauled up on lines and hooks. These remoras are retained and eaten by the crew or sold locally in small markets in places like Hawaii, Fiji and French Polynesia.
Some artisanal fishing boats will also harvest small numbers of remoras in certain locations when other catch is low. But there is no commercial scale harvest focused specifically on remoras anywhere in the world.
Are remoras endangered?
No current remora species are considered endangered or threatened. Most are listed as Least Concern on the IUCN Red List of Threatened Species. However, the lack of directed population surveys makes their true conservation status unclear in some cases.
The common remora and whitesucker remora are the most widespread and abundant species. Since they primarily cling to sharks and other highly migratory pelagic fish, their populations remain diffuse and stable.
The manta remora is considered Near Threatened as its limited habitat range and reliance solely on mantas makes it vulnerable. Loss of manta populations could lead to rapid decline in manta remora numbers.
All remora species could face future population declines if their host organisms became threatened by overfishing, habitat destruction or ship strikes. But currently, flexible host preferences provide a buffer against extinction threats for most remoras.
Remoras are fascinating fish with a unique adhesion mechanism that allows them to hitch rides on sharks, whales, turtles and more. While they have a reputation as pesky hanger-oners, remoras form harmless symbiotic relationships with their hosts that provide transportation and access to food scraps.
Remoras can be eaten and some cultures opportunistically harvest them, but their low meat yield prevents major commercial fishing efforts. If cooked thoroughly, remora meat has a mild, slightly sweet taste comparable to white fish like cod or halibut.
While no remora species are currently considered endangered, loss of their larger host organisms could put them at future risk. But for now, remoras remain abundant in warm oceans across the world, clinging to the bellies of whale sharks, the backs of manta rays, and the fins of oceanic whitetip sharks.