Slimy sculpin facts for kids
Quick facts for kids Slimy sculpin |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Cottus
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| Species: |
cognatus
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| Synonyms | |
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Cottus formosus |
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The slimy sculpin (Cottus cognatus) is a small freshwater fish. It belongs to the Cottidae family, which is the biggest group of sculpins. These fish usually live in cold, rocky streams or lakes. You can find them across North America, including the Great Lakes area and parts of Canada. They also live in cold streams in eastern Siberia, Russia.
Slimy sculpins are often mixed up with their relatives, the Mottled sculpin (Cottus bairdi), and with tubenose gobies. All of these are freshwater fish. The slimy sculpin is active at night. It spends most of its time on the bottom of streams. It hides under rocks and logs, especially when it's time to lay eggs. When it swims, it looks like it's "hopping" along the bottom. This is because it's not a very good swimmer. One reason for this is that it doesn't have a swim bladder. A swim bladder usually helps fish float easily.
Scientists have studied slimy sculpins in waters where there is freshwater acidification. This means the water is becoming more acidic. Sculpins in these waters were less active. They also had fewer babies. Because of this, slimy sculpins are good indicator species. This means they can show us when lakes, ponds, and streams are changing and becoming more acidic.
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Where Slimy Sculpins Live
Slimy sculpins are naturally found in the United States, Canada, and Russia. In North America, you can mostly find them in Lake Superior and its connecting streams. They also live in Lake Michigan and small, cold streams in southwestern Wisconsin. You can find them in the upper Mississippi River basin too.
Other places they live in North America include southeast Minnesota (mostly in the Mississippi River). They are also in northeast Iowa, the upper Columbia River, Alaska, and most of Canada, especially near Ottawa. As mentioned, slimy sculpins also live in eastern Siberia, Russia.
What Slimy Sculpins Look Like
You can easily spot a slimy sculpin by its two separate pelvic fins. Also, it doesn't have any scales! Its first and second dorsal fins are narrow and touch each other. The first dorsal fin has 7 to 9 soft spines. The second one has 16 to 18 fin rays.
The lateral line system helps the slimy sculpin feel the water's pressure. This helps it stay balanced in strong currents. The anal fin has 11 to 13 fin rays. The pelvic fins have 13 to 14 fin rays and are located near its chest. The fish's mouth and snout are wide. They have tiny, cone-shaped teeth in both the upper and lower jaw. They do not have barbels (whisker-like feelers).
Adult slimy sculpins weigh about 3 to 7 grams. They are usually 6.3 to 9.1 centimeters long. The biggest slimy sculpin ever found weighed 16.86 grams and was 12.8 centimeters long. When this fish moves, it's a quick, darting motion. It looks like it's hopping because of its unusual body shape.
The sides, back, and head of slimy sculpins are dark brown or olive green. They have dark, uneven blotches. Their belly is light cream or white. If a slimy sculpin stays still, it blends in so well with its surroundings. It becomes almost impossible to see! Even though they don't have scales, they have a few small prickles near their head, below the lateral line. Slimy sculpins often look very similar to the tubenose goby.
Slimy Sculpin Habitat
Slimy sculpins often live in fast-moving, cold streams with rocky bottoms. They also live in oligotrophic lakes, which are lakes with very clear water and few nutrients. They can even live in slightly salty (brackish) waters. They prefer water temperatures between 9 and 14 degrees Celsius.
These fish are active at night. They usually swim around in deeper waters, from 37 to 108 meters deep. During the time they lay eggs, female sculpins often place their eggs under safe spots. These spots can be large rocks or tree roots at the bottom of lakes or streams. The male sculpin then guards these eggs.
Slimy Sculpin Reproduction
During mating season, male slimy sculpins change color. Their backs and sides become darker. The first dorsal fin turns orange. Having an orange fin makes them easier for predators to spot. But if they survive, it shows females they are strong and healthy. This makes females more attracted to these colorful males.
Males find nesting spots about 12 centimeters wide for the females. They attract females to these spots. The egg-laying usually happens in late April and May. The eggs are laid under protected areas like stones or tree roots. Once the eggs are laid, the male chases the female away. Then he brings a new female to the nest to lay her eggs.
Males protect the nest for 3 to 4 weeks. These nests can hold eggs from many different females. The male guards the eggs until they all hatch. Male slimy sculpins have even been seen protecting their young after they hatch. Slimy sculpins usually live for 4 to 7 years.
What Slimy Sculpins Eat
Slimy sculpins mainly eat small insects that live on the bottom of the water. These "invertebrate benthic insects" make up 85% or more of their diet. They also eat crustaceans (like tiny shrimp), fish eggs, and small fish.
The aquatic insects they eat include mayflies, caddis flies, stoneflies, and dragonflies. Bigger fish that eat slimy sculpins include lake trout, brook trout, salmon, northern pike, and burbot. These fish also live in cool freshwater streams.
Some people think sculpins might eat trout eggs that have come loose from their nests (redds). However, sculpins eating stoneflies actually helps trout. This is because stoneflies also eat trout eggs and young trout. So, sculpin eating stoneflies can protect trout babies.
Conservation Status
The slimy sculpin is currently not a fish that needs a lot of help. Its population is stable, so it does not need special protection or big management plans right now.
