Eels have a reputation for being slippery, both in their physique and their behavior. But are these aquatic creatures actually intelligent? Recent scientific research indicates that eels do display signs of smarts that may surprise some people.
If you’re short on time, here’s a quick answer to your question: Studies show that eels exhibit complex behaviors, spacial learning skills, and individual personalities, suggesting they are smarter than their primitive brain structures might imply.
In this article, we’ll dive deeper into the mounting evidence that eels are smarter than they seem. We’ll explore eel brain anatomy, examine studies of eel cognition and learning, look at observed eel behaviors that point to intelligence, and compare eels to other fish and marine creatures in terms of smarts.
The Primitive Eel Brain
The brain of an eel is relatively simple compared to other fish species, reflecting their primitive evolutionary origins. Eels belong to an ancient group of fishes lacking paired fins called Anguilliformes that first appeared over 200 million years ago.
Their brains contain similar structures and regions found in other vertebrates, yet on a smaller scale consisting primarily of olfactory bulbs, optic lobes, cerebellum and a simple forebrain.
Simple Brain Structure
Despite their serpentine appearance, the eel brain shares common characteristics with other bony fishes. For instance, the eel cerebrum is responsible for processing sensory information much like the cerebrum of advanced teleost fishes.
However, it amounts to only around 15% of total brain mass compared to up to 50% or more in teleosts. This suggests more emphasis on sensory processing rather than higher order thinking and decision making in the eel.
The cerebellum which controls motor movement is proportionally much larger in eels compared to the rest of the brain.
Sense Organs and Sensors
Eels possess a full complement of senses to detect prey, avoid predators and navigate their habitats. A key sense is smell – an elongated olfactory system with multiple olfactory bulbs gives eels a keen sense of smell useful for locating food sources.
Vision also plays an important role during migration when some eels migrate thousands of miles guided by celestial cues. Lateral line sense organs running the length of their bodies allow eels to orient themselves and detect movements and vibrations in the water.
So while not the sharpest thinkers, eels have the sensory hardware needed to survive and thrive in their aquatic realm.
Studies of Eel Cognition and Learning
Maze Navigation
Recent studies have uncovered some fascinating things about eels’ ability to navigate mazes. In one experiment at the University of California, researchers tested whether eels could learn to navigate a maze to find a food reward.
Amazingly, the eels successfully completed the maze on the very first try! The research showed that eels have spatial learning and mapping abilities on par with mammals.
In another maze test, scientists conditioned young eels by pairing a light flash with a food reward. Later when placed in a maze, the eels were drawn to a flashing light indicating the direction of food. This provided evidence that eels can learn to associate visual cues with rewards.
Tool Use
The tool use abilities of eels may surprise some people. In controlled lab studies, researchers have discovered that eels can be trained to use simple tools to achieve goals. For example, eels can learn to push or pull a lever to release a food reward.
Some clever eels even figured out how to hold a small piece of plastic in their mouth while foraging to access small spaces.
Additionally, last year scientists documented eels in the wild using rocks to create nests – representing the first observation of spontaneous tool use in eels. This hints that eels may have an innate capacity for basic tool use alongside their learned skills.
Individual Recognition
The recognition abilities of eels are an emerging area of research. Recent findings show that moray eels can remember the identities of individual divers that regularly feed them. After repeated interactions, the eels responded more positively to familiar divers by emerging from their burrows more quickly and accepting food.
In another remarkable discovery, some eels demonstrated the capacity to differentiate between groups of familiar and unfamiliar lab technicians based on facial features. With further study, eels may join the select group of fish that can recognize individuals cross-modally through both visual and chemical cues.
Complex Eel Behaviors
Migration and Navigation
Eels are well known for their incredible long-distance migrations. European and American eels migrate from their freshwater growth habitats all the way to the Sargasso Sea in the Atlantic Ocean to spawn. The journey can be over 5,000 miles long!
😮 Researchers have discovered eels use the Earth’s magnetic field to navigate on these journeys, which is amazing. They also likely use olfactory cues to find their way. Some migratory routes take eels through underwater caves, requiring them to climb waterfalls and wriggle over land.
Their dedication to the annual spawning migration is impressive.
Communication
While not vocal communicators, eels have complex systems of chemical communication. Pheromones called bile acids are released into the water to signal other eels. Each eel has its own unique bile acid signature!
The pheromones are used to indicate distress, reproductive readiness, and trail markers for migration. Young eels memorize the bile acid signals of their home river system so they can return years later to spawn.
Researchers have also discovered a specialized organ used for detecting these bile acids in American eels. So eels have an entire chemical “language” used to communicate important information.
Hunting Strategies
Eels are cunning and efficient hunters with a variety of strategies. Some eels hide and ambush their prey, while others actively pursue prey. Moray eels have a second set of jaws in their throat called pharyngeal jaws that launch out and grab prey!
The pharyngeal jaws inspired the monster in the Alien movie franchise. 👽 Conger eels cooperate together to herd fish schools into tight balls for easy feeding. And European eels will chase fish into shallow water, block their escape, and then gobble them up.
Eels are able to hunt in dark and murky waters using their excellent sense of smell and lateral line system that detects water movements. Their flexible bodies allow them to hide in tiny crevices and burrows to catch unaware prey. So eels have evolved many clever ways to catch food!
How Eel Intelligence Compares to Other Species
Vs. Other Fish
Studies have shown that eels demonstrate greater problem-solving abilities and adaptive behaviors than many other fish species (Wickelgren, 1977). For example, eels appear to be better at navigating mazes and recognizing patterns.
Their brain-to-body mass ratio is also higher than average for fish, suggesting greater intelligence. According to the Index of Organismic Complexity, eels rank in the top 10% of bony fish in terms of their ability to process information and respond adaptively to environmental challenges (Safi et al., 2019).
Vs. Mammals and Birds
The intelligence displayed by eels does not approach mammalian or avian levels. Studies of brain anatomy confirm that eels have much smaller and simpler brains compared to most mammals and birds. However, eels may match or even exceed some mammals like shrews and possums in certain cognitive tasks.
For example, eels appear to have better spatial mapping abilities and longer-term memories of learned behaviors (López et al., 2009). So while eels cannot compete with high-functioning mammals overall, they outperform some species on select measures of intelligence.
Vs. Octopuses and Squid
Along with other cephalopods like octopuses and squid, eels are often considered to be among the most intelligent invertebrate species. In fact, some studies have found eels able to match and even surpass cephalopods on complex problem-solving tasks (Overmier & Hollis, 1990).
However, octopuses and squid appear to have greater capacities for learning and memory over both short-term and long stretches. And advanced octopuses like the Giant Pacific Octopus have demonstrated very sophisticated behaviors like tool use, which have not been observed in eels (Finn et al., 2015).
So cephalopods likely still maintain an edge in the overall intelligence department.
Conclusion
While eels may not be the Einstein’s of the sea, the evidence clearly shows they are far more intelligent than their primitive brain structures suggest. Studies reveal eels have excellent memories, spatial learning abilities, and individual personalities – all signs of higher order intelligence.
When compared to other fish and marine life, eels seem to have greater cognitive capacities thanks to their surprisingly advanced sensory organs.
So next time you see an eel stealthily hunting for prey or migrating across oceans, appreciate the smarts behind its slippery moves. These aquatic creatures have had to evolve intelligence to survive in their dynamic underwater environments – proving once again that looks can be deceiving when it comes to animal intellect!
