In the spirit of Halloween, Shedd Aquarium has a scary story for you that is all too real: You’re going about your day, living your life, when out of the corner of your eye, you see something unfamiliar. You’re uneasy. You’ve never seen this creature before. You tentatively step toward it when you realize — it’s not alone. A shiver turns your blood cold as you try and count their ever-multiplying numbers. Before you know it, you’re surrounded and there’s no escape from…invasive species!

Feeling scared yet? You’re not the only one. Every day, ecosystems are threatened by invasive species — non-native plants or animals that can destroy vulnerable populations of aquatic life. Even our own Great Lakes are battling with invasive species.

Halloween is the perfect time to share some of the aquarium’s most feared invasive species as well as a few scary animals you can see at Shedd Aquarium. Take a look at our creepy countdown and photos link below, and visit our website to learn more about how you can help marine environments fight back against these ghoulish houseguests.

Sea Lamprey 1. Sea lamprey. These vampires of the deep use their mouth full of sharp teeth to latch onto fishes, feeding on their victims' blood and bodily fluids for hours, days and even weeks. Some fishes die, while survivors are seen with circular scars from the lamprey’s bite. Originally from the Atlantic Ocean, they’ve made their way to the Great Lakes. If current measures are not maintained to control the sea lamprey population, the Great Lakes fishing industry could suffer a collapse.

Asian Carp

 2. Asian carp. Their silent invasion of the Great Lakes is imminent. They have the potential to cause severe damage because they eat plankton for food, leading to reductions in populations of native species that rely on the same plankton for survival. Once Asian carp grow to a certain size, there are no predators capable of eating them. These invaders not only disrupt the food chain and push out native fishes, they’re also extremely dangerous. The silver carp has the ability to leap high out of the water, occasionally injuring boat passengers.

Spotted Wolffish

 3. Spotted wolfish. Lurking deep in the ocean lays a jagged-tooth, bulging-eyed creature capable of crushing clams, scallops, crabs and sea urchins with its canine-like jowls. The spotted wolffish lives on the seafloor, and although it’s not commercially fished, it’s unintentionally caught in nets as bycatch and threatened by modern fishing practices like dredging, a practice that adds to the destruction of the seafloor. Spotted wolffish help keep sea urchin populations from exploding and destroying kelp forests, which play a key role in the environment by consuming carbon dioxide from the atmosphere.

Spotted Jelly

 4. Australian spotted jelly. First spotted in the Gulf of Mexico at the brink of an outbreak 14 years ago, this jelly costs the fishing industry millions of dollars by feeding on eggs and larvae of fishes, crabs and shrimp, clogging fishing nets and damaging boat intakes and fishing gear.


 5. Hellbender. North America’s largest salamander comes from an ancient amphibian lineage that’s been around for more than 160 million years. Located from central New York to northern Arkansas, these near-threatened species depend on water just as much as humans do because they use their skin to absorb oxygen directly from the water itself. A healthy population is a good indicator of good water quality. The hellbender population is in decline, however, which can only mean one thing.

Blacktip Reef Shark

 6. Blacktip reef shark. Sharks like the blacktip reef shark serve a purpose by keeping fish populations under control. Blacktips are often caught in fishing nets as bycatch, and their populations are declining. They’re also impacted by the destruction of coral reefs, which are important feeding grounds for the sharks.

Round Goby

 7. Round goby. This aggressive invader eats the eggs of other fishes. After invading the Great Lakes more than 20 years ago, the goby continues to disrupt the food web with severe consequences. The goby is linked to declining populations of other bottom-dwellers, using a sensory system that helps it detect water movement in complete darkness.

Red Lionfish

 8. The red lionfish. A native of the Indo-Pacific, this species was probably introduced to the southeast coast of the United States, the Caribbean and Gulf of Mexico as released or escaped pets. The zebra-striped invader is reproducing fast, and there’s no clear way to stop it. Since Atlantic fishes lack instinct to stay away from the invader, the red lionfish is eating its way through the Atlantic, slowly depleting ocean life.

Zebra Mussel

  9. Zebra mussel. This is one of the most damaging creatures to the Great Lakes. Originally from the Caspian Sea region, zebra mussels are damaging local ecosystems by eating plankton available for other aquatic life and causing pipe damage to water and power plants. They have few natural predators.

 10. Humans. Aquatic ecosystems suffered overfishing partially due to improved fishing technology. Without enough time to replenish the fish supply, the stocks remain exploited and are unable to produce any more fishes than what is currently available.

Visit our Halloween page for links to more features—frightening, fantastic and fun!