Answer:
Explain that in this activity students will use a series of videos, images, and scenarios to identify and discuss examples of ecological and symbiotic relationships in the ocean. Write the following terms on the board: competition, predation, symbiosis, mutualism, commensalism, and parasitism. Do not include the definitions yet. First, ask students to identify the root words and brainstorm what types of ecological and symbiotic relationships the terms describe. Then, review the definitions of the terms. Point out that the term symbiosis is an overarching term for mutualism, commensalism, and parasitism and that the ecological relationships predation and competition are not generally considered to be symbiotic.
competition—when two or more organisms rely on the same environmental resource
predation—behavior of one animal feeding on another
symbiosis—the close relationship of two dissimilar organisms
mutualism—a symbiotic relationship where both organisms benefit
commensalism—a symbiotic relationship where one organism benefits and one does not benefit but is unharmed
parasitism—a symbiotic relationship where one organism benefits and one is harmed
2. Build background about National Geographic Crittercam.
Explain to students that they will watch footage from a National Geographic project called Crittercam. Crittercam’s goal is to help researchers understand the day-to-day lives and ecological relationships of different species. Scientists fit wild animals with a GPS tracker and a combination video and audio recorder with environmental data instruments to measure such things as depth, temperature, and acceleration—which allow the study of animal behavior without interference by human observers. Ask students to think about the benefits of studying animal behavior and ecological interactions without interference by human observers.
3. Have students use a Crittercam video to identify ecological relationships.
Show students the National Geographic video “Fish Thieves Take Rare Seals’ Prey” (3.5 minutes), in which an endangered Hawaiian monk seal preys upon and competes for fish and invertebrates on the seafloor at 80 meters (262 feet) deep. Ask: What is the ecological relationship between the monk seal and the octopus/eel/trigger fish? (predator/prey) Ask: What is the ecological relationship between the monk seal and the jacks/sharks? (competition) Ask students to again think about and discuss the benefits of studying animal behavior and ecological interactions without interference by human observers. Elicit from students that Crittercam allows researchers to examine the behavior and interactions of marine species that they normally would be unable to observe.
4. Have students view videos to identify symbiotic relationships.
Show students the three videos of different marine species interactions. After each video, have the class identify and discuss the symbiotic relationships they observed.
“Caribbean Cleaners” (2.5 minutes)—mutualism
“Giving Fish a Bath” (5.5 minutes)—parasitism
“Clownfish and Sea Anemone Partnership” (1.5 minutes)—mutualism
Ask: What type of symbiotic relationship was not shown in the videos? (commensalism)
5. Use a National Geographic image to explore commensalism and discuss the origins of Crittercam.
Display the image “lemon shark” in the resource carousel and have students observe it closely. Ask: Other than the shark, are there any other organisms you see? Elicit from students that the shark and the remoras, the smaller fish below the shark, have a symbiotic relationship called commensalism, where the remoras benefit from holding onto the shark, but neither species is harmed. Tell students that this commensal relationship is why Greg Marshall, marine biologist and filmmaker, invented Crittercam. In 1986, a shark approached him during a dive near Belize. Marshall noticed a remora clinging to a shark, and as he watched the shark disappear, it occurred to him that if he could put a camera in the place of the remora, he could see the shark's behavior unfold without disturbing the shark. Explain that with Crittercam, Marshall learned that remoras attach themselves to predatory fish like sharks for two reasons: a free ride and protection due to hanging onto a feared predator. The shark is not affected in the process since remoras eat only leftover food from the shark.
