Lesson Plan

Harmful Marine Debris

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Grade Level:
Fourth Grade-Eighth Grade
Biology: Animals, Earth Science, Environment, Reading, Visual Arts, Wildlife Biology, Wildlife Management
45 minutes
Group Size:
Up to 24 (4-8 breakout groups)
National/State Standards:
Standard 7: Students examine organisms’ structures and functions for life processes, including growth and reproduction. (ASDOE Elementary Science Standards: Grade 4-8, pp. 41-73)


Students complete a form that requires them to make decisions about how severely different types of marine debris affect animals, people, vessels, and habitat. As a class, results are totaled and analyzed to determine which types of marine debris are most harmful to the different categorizes.


Students will be able to:

1. Define the vocabulary term marine debris.

2. Explore the effects of marine debris on animals, people, vessels, and habitats.

3. Identify which marine debris is most harmful.



Marine debris can have serious impacts on both marine wildlife and humans. Debris can entangle, maim, and even drown many wildlife species. Animals can also mistake some debris for food; once ingested, these materials can cause starvation and/ or choking. Although almost any species can be harmed by marine debris, certain species – including seals, sea lions, seabirds and sea turtles – are more susceptible to its dangers than others. For humans, marine debris can be a health and safety hazard. The impacts of marine debris can also result in economic hardships for coastal communities related to tourism and the fishing industry.

The two primary threats that marine debris poses to marine wildlife are entanglement and ingestion. Entanglement results when an animal becomes encircled or ensnared by debris. Some entanglement occurs when the animal is attracted to the debris as part of its normal behavior or out of curiosity. For example, an animal may try to play with a piece of marine debris or use it for shelter. Some animals, such as seabirds, may see fish caught in a net as a source of food, and become entangled while going after the fish.

Entanglement is harmful to wildlife for several reasons:
a. It can cause wounds that can lead to infections or loss of limbs.
b. It may cause strangulation, choking, or suffocation.
c. It can impair an animal’s ability to swim, which may lead to drowning, or make it difficult for the animal to move, find food, and escape from predators.

Ingestion occurs when an animal swallows marine debris. Ingestion sometimes happens accidentally, but generally animals ingest debris because it looks like food. For example, a floating plastic baggie can look like a jellyfish, and resin pellets (i.e., small, round pellets that are the raw form of plastic, which are melted and used to form plastic products) can resemble fish eggs. Ingestion can lead to choking, starvation or malnutrition if the ingested items block the intestinal tract and prevent digestion, or accumulate in the digestive tract and make the animal feel “full,” lessening its desire to feed. Ingestion of sharp objects can damage the digestive tract or stomach lining and cause infection or pain. Ingested items may also block air passages and prevent breathing, causing the animal to suffocate.

Marine mammals, sea turtles, birds, fish, and crustaceans all have been affected by marine debris through entanglement or ingestion. Unfortunately, many of the species most vulnerable to the impacts of marine debris are endangered or threatened. Endangered species are plants or animals that are in immediate danger of becoming extinct because their population levels are so low. Threatened species are plants or animals that may become endangered in the near future.


1. Pencil and/or pen

Handouts & Worksheets
1. "How Harmful Is it?" handout



Last updated: February 28, 2015