Implement this lesson:

Use this lesson when discussing animal ecosystems, habitats, or other environmental TEKs. This lesson can be used as part of a larger local theme i.e. Oceans Week. It can also be used for a jellyfish themed day. The duration of this lesson can vary based on student and teacher needs.

Learning Objective:

Students will be able to learn about one of the most common animals found in local saltwater habitats, the jellyfish. They will create an art project using their knowledge.

Texas Essential Knowledge and Skills (TEKS)

Overview

There are four common jellyfish that students will see when they go into the bays or beaches. There are numerous other species including species that are arriving with warming ocean temperatures.

Moon Jellyfish (Aurelia aurita)

The moon jellyfish is a common and easily recognized jellyfish found in oceans around the world. It gets its name from its round, translucent body that looks like a glowing moon.

Appearance and Behavior

• Grows up to 25–40 cm (10–16 inches) in diameter
• Has a bell-shaped, see-through body with four horseshoe-shaped gonads visible inside
• Moves slowly by pulsing its bell, but mostly drifts with ocean currents
• Has short, fine tentacles around the bell and four long oral arms for feeding
• Glows slightly in the dark due to bioluminescence

Diet and Feeding

• Eats plankton, small fish, fish eggs, and tiny crustaceans
• Uses mucus on its bell and tentacles to trap food
• Food is moved to the mouth using its oral arms
• Lacks a brain or heart, but has a nerve net to detect light and movement

Life Cycle and Reproduction

• Has a complex life cycle with both sexual and asexual stages
• Adult jellyfish (called medusa) release eggs and sperm into the water
• Fertilized eggs develop into larvae (planula)
• Larvae settle on a surface and grow into polyps, which reproduce asexually
• Polyps release tiny jellyfish called ephyrae, which grow into adult medusae

Habitat and Range

• Found in coastal waters and harbors all over the world
• Prefers temperate and tropical oceans
• Can survive in low-oxygen or low-salinity waters, making it very adaptable
• Often found floating in large blooms (groups), especially in warm months

Interesting Facts

• Can sting, but its sting is mild and usually harmless to humans
• Moon jellies are an important part of the marine food web, feeding fish and sea turtles
• They are often used in aquariums and scientific studies
• Populations are increasing in some areas due to overfishing and climate change, which reduce their predators and competitors

Atlantic Sea Nettle Jellyfish (Chrysaora quinquecirrha)

The Atlantic sea nettle is a colorful jellyfish commonly found along the east coast of the United States, especially in the Chesapeake Bay and Gulf of Mexico. It’s known for its long tentacles and painful sting.

Appearance and Behavior

• Bell size: up to 25–30 cm (10–12 inches) across
• Bell is translucent with a whitish or pinkish tint, often marked with reddish-brown stripes
• Has long tentacles and frilly oral arms extending up to several feet
• Moves by pulsing its bell, but mostly drifts with the ocean currents
• Often seen floating in warm, coastal waters during summer and early fall

Diet and Feeding

• Eats zooplankton, small fish, fish eggs, and other jellyfish
• Uses stinging cells (nematocysts) on its tentacles to paralyze prey
• Tentacles bring food to its mouth located under the bell
• Helps control plankton and fish larvae populations in coastal ecosystems

Life Cycle and Reproduction

• Has a two-part life cycle:
  • Medusa stage (free-floating adult jellyfish)
  • Polyp stage (attached to a surface and reproduces asexually)
• Adults release sperm and eggs into the water
• Fertilized eggs become larvae (planula), which attach and grow into polyps
• Polyps release tiny jellyfish called ephyrae, which grow into adults

Habitat and Range

• Found in the western Atlantic Ocean, from New England to Brazil
• Common in bays, estuaries, harbors, and coastal waters
• Prefers brackish water (a mix of salt and freshwater)
• Can tolerate a wide range of salinity and temperature, making it very adaptable

Interesting Facts

• Sting can be painful, like a bee sting, and may cause a rash or irritation in humans
• Sea turtles and sunfish often eat them
• Often mistaken for other jellyfish but identified by its striped bell and long, lacy tentacles
• Blooms (large groups) of sea nettles can affect swimming, fishing, and tourism
• Play a role in balancing fish and plankton populations in coastal waters

Cabbage Head Jellyfish (Stomolophus meleagris)

The cabbage head jellyfish is a round, dome-shaped jellyfish that lives in warm coastal waters. It’s named for its bulbous, cabbage-like bell and is one of the most harmless jellyfish to humans.

Appearance and Behavior

• Bell size: up to 25 cm (10 inches) in diameter
• Bell is firm, round, and smooth, often white or milky with brown or purplish edges
• Lacks long tentacles—has short, stubby arms underneath the bell
• Moves by pulsing quickly, often seen in large swarms
• Often found in shallow waters during spring and summer

Diet and Feeding

• Eats zooplankton, small fish, and eggs
• Uses mucus and sticky oral arms to trap food
• Does not have a strong sting—mild or no effect on humans
• Helps filter small organisms from the water and is an important part of the food chain

Life Cycle and Reproduction

• Follows a typical jellyfish life cycle with:
  • Medusa stage (adult jellyfish)
  • Polyp stage (attached to a surface)
• Adults release sperm and eggs into the water
• Fertilized eggs become larvae, which settle and grow into polyps
• Polyps release ephyrae, which grow into adult cabbage head jellyfish

Habitat and Range

• Found in the western Atlantic Ocean, Gulf of Mexico, and Caribbean Sea
• Prefers warm, shallow coastal waters
• Often seen in large groups (blooms), especially near the shore
• Tolerates a range of temperatures and salinity levels

Interesting Facts

• Also called cannonball jellyfish due to its shape and firmness
• Sting is very mild—safe to swim near in most cases
• Eaten by leatherback sea turtles and other predators
• Harvested in some countries (like Asia) for use in human food and medicine
• Plays an important role in marine ecosystems by helping control plankton levels

Portuguese Man o’ War (Physalia physalis)

Often mistaken for a jellyfish, but it’s actually a siphonophore. The Portuguese man o’ war is a marine animal made up of a colony of organisms working together. It floats on the ocean’s surface and is famous for its colorful balloon-like float and long, stinging tentacles.

Appearance and Behavior

• Float (called a pneumatophore) is about 9–30 cm (3.5–12 inches) long
• Tentacles can extend up to 30 meters (100 feet), though usually much shorter
• Float is blue, purple, or pink and rests above the water
• Tentacles hang below and contain thousands of stinging cells
• Cannot swim—moves with wind and ocean currents

Diet and Feeding

• Eats small fish, plankton, and crustaceans
• Tentacles have venom-filled stinging cells (nematocysts) to paralyze prey
• Tentacles pull prey toward its digestive polyps
• Stings are used for both hunting and defense

Life Cycle and Reproduction

• The man o’ war is a siphonophore, made of four specialized polyps that each serve a role (floating, feeding, reproducing, or stinging)
• Reproduces sexually, but details are not fully understood
• Males and females release sperm and eggs into the water
• Fertilized eggs develop into new colonies
• Does not have a medusa or polyp stage like true jellyfish

Habitat and Range

• Found in warm ocean waters around the world
• Common in the Atlantic Ocean, Gulf of Mexico, Caribbean, and even the Indian and Pacific Oceans
• Often seen in tropical and subtropical regions, washed up on beaches
• Floats in open waters but may be pushed near shore by winds

Interesting Facts

• Not a true jellyfish but closely related
• Can still sting even when washed up on shore
• Sting is very painful and can cause red welts, swelling, nausea, or allergic reactions
• Rarely deadly but should always be avoided
• Predators include the blue sea slug (Glaucus atlanticus) and loggerhead sea turtles
• Its name comes from its float, which resembles an old Portuguese warship under sail

Evaluations:

• Student participation
• Student created craft

Extensions:

• Students write a fiction or nonfiction story about a jellyfish
• Students create their own model of a jellyfish using maker space materials
• Students complete various jellyfish worksheets and lessons
• Students can read other books or research about other types of jellyfish

Lesson created by: Yessica Azua, Amy Tapia, Tanya Schillinger, Shawne Estevanes,