In this second part of our two-part series highlighting the world’s least-speedy animals, we shift our focus to some of the slowest animals beneath the waves.
This article looks at 10 aquatic animals known for their sluggish movements.
Some of them use a lack of speed as a strategy to conserve energy.
Many of these creatures form symbiotic bonds with other organisms by attaching themselves to larger structures.
Just like their terrestrial counterparts, many aquatic creatures also travel at a leisurely pace. From graceful manatees to giant sea turtles, let’s take a journey beneath the sea and take a look at 10 of the slowest water animals.
1. Manatee
Commonly known as sea cows, manatees (Trichechus) can be found in the shallow, marshy coastal areas and rivers of the Caribbean, the Gulf of Mexico, the Amazon basin, and West Africa.
These gentle giants of the ocean, considered one of the elephants’ closest living relatives, usually travel at a pace of three to five miles per hour (five to eight kilometers per hour).
They combine a substantial size, reaching up to 13 feet (3.9 meters) in length and 3,500 pounds in weight, with a limited enthusiasm for movement. However, when in a hurry, they can reach a speed of 20 miles per hour (32 kilometers per hour) in short bursts.
These large aquatic animals generally swim at a rate of 3 to 5 miles per hour.
Their slow pace and curious nature have led to many deadly collisions with boats and ships. A 2023 study identified boat strikes as a growing cause of manatee deaths in Belize.
“We knew that boat strikes were happening, but this study provides strong quantitative evidence of boat strikes as an increasing source of mortality for manatees in Belize, and it shows the areas where the risk is greatest,” said Marm Kilpatrick, Ph.D., professor of ecology and evolutionary biology at UC Santa Cruz in a statement.
2. Sea anemone
Sea Anemones (Actiniaria), which are closely related to coral, sea pens, and jellyfish, are stinging marine carnivores that spend most of their lives attached to coral reefs or rocks on the sea floor.
Once anchored, these soft-bodied creatures rarely detach and compensate for their lack of mobility by catching passing prey, mostly fish and invertebrates, using their venomous tentacles.
Sea anemones may move in response to predators or in unfavorable conditions.
Found throughout the world’s oceans, from the shores to depths of 32,800 feet (10,000 meters), sea anemones move at a pace of just four to 10 inches per hour using their singular foot, known as a pedal disc.
3. Dwarf seahorse
The dwarf seahorse (Hippocampus zosterae) is the third smallest seahorse species, reaching maximum lengths of just around 1.7 inches (4.2 centimeters). It is native to seagrass beds in the Gulf of Mexico, the Atlantic Coast of Florida, and the Caribbean.
Limited by its rigid body structure, it is considered the world’s slowest-moving fish as it never achieves speeds of more than five feet (0.016 kilometers) per hour, according to the Guinness World Records.
Sadly, their slow pace also makes them an easy catch, whether unintentionally by fishermen or for commercial trade.
The dwarf seahorse is the slowest-moving fish, with a top speed of about 5 feet (1.5 meters) per hour.
Since seahorses are unable to navigate against strong currents, they clutch onto coral and marine plants using their prehensile tails to prevent being swept away.
According to a 2023 study by the University of Texas, dwarf seahorses have heads perfectly designed to swiftly sneak up on prey without making waves as they move.
“A seahorse is one the slowest swimming fish that we know of, but it’s able to capture prey that swims at incredible speeds for their size,” said Brad Gemmell, Ph.D., research associate at the University of Texas Marine Science Institute.
4. Starfish
Also referred to as sea stars, starfish (Asteroidea) are marine invertebrates living in saltwater and the world’s oceans.
They move using the tiny tube feet found on the underside of their bodies. They usually crawl at around six inches (15 centimeters) per minute or 0.005 miles (0.009 kilometers) per hour.
Due to their incredibly slow movement, starfish often rely on ocean currents to assist them in covering greater distances.
Starfish move around underwater by using their wiggly tube feet
Greenland sharks (Somniosus microcephalus) are known for being the longest-living vertebrates, with a lifespan extending to at least 250 years. A female shark with an estimated age of up to 512 years old was once found.
Native to the cold depths of the Arctic and North Atlantic Oceans, these sharks grow very slowly and only reach sexual maturity at around 100.
The shark’s slow metabolic rate could potentially explain its slow growth, delayed aging, and its sluggish top speed of under 1.8 miles (2.9 kilometers) per hour.
6. Green sea turtles
Found in the Atlantic, Pacific, and Indian Oceans, green sea turtles (Chelonia mydas) are notoriously slow swimmers, traveling at average speeds of between 1.5 and 6.3 miles per hour (2.4 and 10.1 kilometers per hour).
While they can occasionally reach speeds of 22 miles per hour (35.4 kilometers per hour), these bursts are relatively short and unsustainable over longer periods. Typically, they occur when a green sea turtle is reacting to a disturbance or trying to evade potential threats.
Green sea turtles swim at rates of up to 6.3 miles per hour on average.
Green sea turtles are classified as ‘Endangered‘ on IUCN’s Red List, with recent research stating that rising global temperatures are affecting the sex ratios of their clutches, leading to a shortage of males.
“Sea turtles’ embryos developing in their eggs have temperature-dependent sex determination, which means that more and more develop into females as temperatures keep rising,” says Arthur Barraza, Ph.D., a researcher at Griffith University, in a statement.
7. Jellyfish
Commonly known as sea jellies, jellyfish (Scyphozoa) are among the oldest multicellular animals on the planet. They lack central brains, blood, and even hearts, and 95 percent of their body is made of water.
A jellyfish moves by expanding and squeezing its bell. As the bell contracts, two rings, or vortexes, of water are created. The jellyfish moves through the first ring, and as the jellyfish’s bell relaxes, the second ring rolls under the edge of the bell and spins faster. This sucks water in and pushes the jellyfish, propelling it forward.
Despite being able to move more quickly, according to a 2020 study published in the journal Science Advances, jellyfish usually swim at rates of about 0.8 inches (2 centimeters) per second.
Jellyfish typically cover up to 0.8 inches per second.
“We’ve shown that they’re capable of moving much faster than they normally do, without an undue cost on their metabolism,” said Nicole Xu, Stanford graduate student and co-author of the study.
“This reveals that jellyfish possess an untapped ability for faster, more efficient swimming. They just don’t usually have a reason to do so,” Xu added.
8. Nudibranchs
These soft-bodied marine animals, also known as sea slugs, are slow-moving predators related to snails. Their Latin name, Nudibranchia, literally translates to ‘naked gills’ because of their exposed breathing apparatus.
Known for their wide range of shapes and colors, there are more than 3,000 species of Nudibranchs worldwide. “Nudibranchs have always been a marine marvel with their dazzling color diversity,” says Terry Gosliner, Ph.D., senior curator at the California Academy of Sciences.
Nudibranchs move at a speed of around one foot-an-hour as the make their way across the seabed.
Similarly to their snail cousins, nudibranchs move by contracting their one flat, broad muscle called a foot. They navigate across the ocean floor at a maximum speed of 1 foot (0.3 meters per hour).
9. Lobsters
Unhurried lobsters (Nephropidae) reside on the ocean floor, where they use their eight walking legs to find crabs, mussels, clams, starfish, sea urchins, and various marine worms to munch on.
While lobsters are typically slow-moving due to the size of their exoskeleton, they can achieve speeds of up to 11 miles per hour (17.7 kilometers per hour) when threatened. They usually rely on walking to move around rather than swimming.
Lobsters are sluggish because they are weighed down by their armor.
Researchers tracking lobster migrations year-round state that these marine crustaceans usually move into deeper water in late autumn due to water temperatures.
“They are very mobile animals and move around to avoid bad conditions,” said Winsor Watson, Ph.D., professor of zoology at the University of New Hampshire, in a press release.
10. Sea urchins
Simple sea urchins (Echinoidea), which possess no visual organs or central nervous system, typically move at an average speed of 3.1 inches (8 centimeters) a minute.
They usually spend their days nestled in a rock pit that they are believed to carve out themselves and leave briefly while searching for food.
Sea urchins move at a speed of 3 inches a minute to find food and return to their resting point.
However, according to research published in the journal BMC Movement Ecology, fear prompts sea urchins to go ballistic. When exposed to the chemical stimulus of the predator, these spiny, rounded echinoderms nearly doubled their speed at 5.9 inches (15 centimeters) a minute.
“In short, sea urchins can perceive the chemistry of their predators and react instantly by changing their movement patterns,” said Jordi Pagès, Ph.D., a biologist at the University of Barcelona and lead author of the study in a statement. “That is, they fear the predators and react accordingly.”
RECOMMENDED ARTICLES
0COMMENT
NEWSLETTER
The Blueprint Daily
Stay up-to-date on engineering, tech, space, and science news with The Blueprint.
Georgina Jedikovska Georgina Jedikovska, journalist, plant engineer, oenophile and foodie. Based in Skopje, North Macedonia. Holds an MSc. degree in Horticultural Engineering, with a specialization in viticulture and oenology. Loves travelling, exploring new cultures, a good read, great food and flavorful wines. Enjoys writing about archaeology, history, and environmental sciences.
0