Marine Fauna Honor

Nature Study

Requirements

1. Research and describe the importance of marine fauna to the balance of the marine ecosystem.

   Answer: Marine fauna is essential to the balance of the marine ecosystem: 1) it sustains the food chain — predators (sharks, dolphins) control the population of fish and herbivores, preventing imbalances; 2) phytoplankton and zooplankton are the base of the entire food web and produce about half of the planet's oxygen through photosynthesis; 3) it recycles nutrients — remains and waste are decomposed and reused; 4) coral reefs harbor great biodiversity and protect the coastline; 5) filter-feeding animals (sponges, mollusks) clean the water. The removal or imbalance of any group affects the entire chain. — Each species has an ecological role. Sharks control populations; whales pump nutrients from the bottom to the surface; turtles keep dunes healthy. Losing any one of them unbalances the whole system.

2. What is the effect of the large concentration of plastic on marine fauna?

   Answer: Animals ingest plastic mistaking it for food (turtles eat bags thinking they are jellyfish), which clogs the digestive system and kills them. Microplastics contaminate the entire food chain, and nets (suffocating fish and mammals). — The UN estimates that 11 million tons of plastic reach the ocean each year. 90% of seabirds have plastic in their stomach. Microplastics have already been detected in table salt and in human drinking water.

3. Find out how you can help preserve life in the seas.

   Answer: You can help by reducing the use of disposable plastic, disposing of waste correctly, and never pouring oil down the sink. Take part in beach cleanup efforts and avoid consuming products made from corals, rare shells, or turtles. — About 8 million tons of plastic reach the oceans each year and injure or kill more than 100 thousand marine mammals annually, according to UN Environment. Small daily actions reduce this pressure on the ecosystems.

4. Define the main characteristics of the groups below and give 3 examples of each:
   • Crustaceans
   • Coelenterate
   • Mollusks
   • Cetaceans
   • Echinoderms
   • Fish

   Answer: 1) Crustaceans: have a rigid exoskeleton (carapace) and jointed legs, with a body divided into segments and antennae. Examples: shrimp, crab, lobster. 2) Coelenterates (cnidarians): have a gelatinous body with radial symmetry and stinging cells (cnidocytes) for defense and capturing prey. Examples: jellyfish, sea anemone, coral. 3) Mollusks: have a soft body, usually protected by a calcareous shell, and a muscular foot for locomotion. Examples: octopus, squid, sea snail. 4) Cetaceans: are marine mammals that breathe through lungs, are warm-blooded, and nurse their young. Examples: whale, dolphin, orca. 5) Echinoderms: have radial symmetry (usually in five parts), spiny skin, and a system of tube feet. Examples: starfish, sea urchin, sea cucumber. 6) Fish: are cold-blooded aquatic vertebrates that breathe through gills, have fins, and a body usually covered with scales. Examples: tuna, sardine, shark. — Each group is defined by the presence or absence of key characteristics: exoskeleton, stinging cells, mantle, mammary glands, radial symmetry, and gills. This grouping follows the standard taxonomy used by marine biologists.

5. Select 3 invertebrate species and 3 vertebrate species of marine fauna and answer:
   • Common name
   • Scientific name
   • Species
   • Location
   • Types of food
   • Role in marine fauna

   Answer: For each chosen species, record the common name (e.g., octopus, starfish, jellyfish, dolphin, shark, tuna), the scientific name in Latin, the taxonomic species, the geographic location, the types of food, and the ecological role in the marine ecosystem. — Linnaeus's binomial taxonomy uses genus and species in Latin, such as Octopus vulgaris for the common octopus. Knowing feeding habits and ecological roles helps in understanding food chains and the balance of marine ecosystems.

6. Interview a biologist and find out the type of reproduction of the groups of animals mentioned in the previous question.

   Answer: You should schedule an interview with a biologist and ask about the reproduction of each group: most marine invertebrates use external fertilization, fish generally spawn in the water, and cetaceans are viviparous with internal gestation and nursing of their young. — External fertilization is typical of many invertebrates and fish, in which gametes are released into the water. Cetaceans, being mammals, have internal fertilization, prolonged gestation, and nurse their young, like any land mammal.

7. What are poriferans and why are they called filter feeders?

   Answer: Poriferans are sea sponges, aquatic animals without true tissues and full of pores throughout the body. They are called filter feeders because they draw water in through their pores, retain food particles and microorganisms, and expel the clean water through the osculum. — The name porifera comes from the Latin porus (pore) + ferre (to bear). An average sponge filters about 1,500 times its own volume of water per day, acting as a natural purifier of reefs and oceans.

8. State the difference between corals and sea sponges. What is their importance to the environment?

   Answer: Difference: corals are cnidarians, animals with stinging tentacles (cnidocytes) that capture food actively and form colonies with a calcium carbonate skeleton (reefs); sponges are poriferans, simple animals without true tissues, fixed in place, that feed passively by filtering water through their pores. Importance to the environment: corals form reefs that harbor great marine biodiversity (a nursery for fish and invertebrates) and protect the coastline from wave erosion; sponges filter and purify seawater, retaining particles and microorganisms, and also serve as shelter for small animals. — Coral reefs cover less than 1% of the ocean but harbor about 25% of marine life, according to UNESCO. Sponges filter thousands of times their volume daily, contributing to water quality in coastal ecosystems.

9. Explain what benthos, plankton, and nekton are.

   Answer: Benthos: organisms that live on the sea floor, fixed or crawling on the substrate (starfish, crabs, sponges, corals, oysters). Plankton: generally microscopic beings that float adrift, carried by the currents because they lack the strength to swim against them — divided into phytoplankton (plant, photosynthesizing) and zooplankton (animal). Nekton: animals that actively swim and move on their own, overcoming the currents (fish, sharks, dolphins, whales, squids, turtles). — These three groups describe where and how organisms live in the water column. Plankton is the base of the marine food chain — phytoplankton produces about half of the planet's oxygen through photosynthesis.

10. Observe a marine animal for about 30 minutes. Write a report describing what you observed.

    Answer: Direct observation is a scientific technique called ethology, which studies animal behavior in its environment. Konrad Lorenz and Niko Tinbergen won the 1973 Nobel Prize for developing this method of behavioral research.

11. Watch a video of at least 30 minutes about marine life. Write a report on the video.

    Answer: You should watch a documentary or educational video about marine life of at least 30 minutes. In the report, note the title, source, main species mentioned, ecosystems shown, threats presented, and what new things you learned. — Documentaries by BBC Earth, National Geographic, and Discovery Channel are reliable sources and have scientific validation. This type of media helps in getting to know species and environments that would hardly be seen in person.