Questions and Answers
What are general characteristics of class Anthozoa?
How many mouth openings do anthozoans have?
1
Where are the tentacles located on anthozoans?
Surrounding the mouth
How do anthozoans move?
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Describe the feeding process of anthozoans.
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How do anthozoans breathe?
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How do anthozoans protect themselves?
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What are the two forms of reproduction in anthozoans?
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Describe sexual reproduction in anthozoans.
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Describe asexual reproduction in anthozoans.
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What type of skeleton does a sea anemone have?
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How does sexual reproduction benefit anthozoans?
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How do corals differ from anemones?
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What is the difference between soft and hard coral?
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Do all corals build reefs?
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What physical requirements are necessary for coral reefs to flourish?
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Describe the symbiotic relationship between reef-building corals and zooxanthellae.
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Why are coral reefs found in waters less than 300 feet deep?
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What are corals?
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When do corals reproduce?
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What is the composition of coral skeletons?
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Why do corals have translucent tentacles?
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What supports the diverse ecosystem within coral reefs?
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What are the three main types of coral reefs?
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Why are coral reefs important?
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How do coral reefs form?
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What are common threats to coral reefs?
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What enables planula larvae to swim?
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What percentage of energy do anthozoans derive from zooxanthellae?
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Study Notes
General Characteristics of Anthozoa
- Mostly sessile organisms primarily existing as polyps.
- Lack alternation of generations and exhibit polymorphism.
- One oral opening for intake and expulsion of food and waste.
Tentacles and Movement
- Tentacles encircle the mouth, aiding in feeding and protection.
- Generally sessile; movement is minimal and only when necessary.
- Utilize a pedal disc to anchor themselves to surfaces.
Feeding and Digestion
- Tentacles with nematocytes sting and paralyze prey for ingestion.
- Food enters the gastrovascular cavity for digestion; undigested matter is expelled through the mouth.
Respiration
- Respiration occurs via diffusion as cnidarians lack lungs and a heart.
Protective Structures
- Tentacles house cnidocytes containing nematocytes, which release neurotoxins for defense and prey capture.
Reproductive Strategies
- Reproduction can be asexual or sexual.
- Sexual reproduction involves external fertilization, leading to planula larvae formation.
- Asexual methods include budding, longitudinal fission, pedal laceration, and fragmentation.
Skeleton and Coral Structures
- Sea anemones possess a hydrostatic skeleton maintained by osmotic pressure.
- Corals can be hard (secreting a skeletal cup) or soft (connecting tissue in colonies).
Coral Reefs
- Not all corals contribute to reef formation; most reef-building occurs with stony corals.
- Healthy coral reefs flourish in bright, clear water with salinity and temperature conditions around 70°F.
Symbiotic Relationships
- Reef-building corals and zooxanthellae engage in mutualism: zooxanthellae provide photosynthetic benefits, while corals offer habitat.
- This relationship supports coral health, coloration, and skeletal growth.
Habitat Requirements
- Coral reefs thrive in shallow waters (less than 300 feet deep) where light penetration is sufficient for photosynthesis.
History and Classification
- Historically misclassified as plants until the 19th century, corals are recognized as animals, hosting symbiotic zooxanthellae.
- Corals reproduce mostly at night and consist primarily of limestone structures made from calcium and carbon.
Importance of Coral Reefs
- Serve as vital ecosystems for marine life, housing approximately 25% of marine species while covering only 7% of the ocean.
- Provide ecological benefits by safeguarding shorelines and materials for valuable resources (e.g., medicines).
Types of Corals and Reefs
- Three main types of coral reefs: fringing reefs, barrier reefs, and atolls.
- Reefs develop very slowly—approximately 1-16 feet every thousand years.
Threats to Coral Reefs
- Coral bleaching leads to "white corals," indicating dead corals due to stressors that kill zooxanthellae.
- Physical damage from boat anchoring and other human activities jeopardizes reef health.
Larval Mobility and Energy Sources
- Planula larvae swim using cilia for propulsion.
- Corals obtain 90% of their energy from symbiotic zooxanthellae and 10% from ingested food/water.
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Description
Test your knowledge on the general features, feeding mechanisms, and reproductive strategies of Anthozoa. This quiz will cover essential aspects like movement, digestion, and protective structures within these fascinating organisms. Perfect for students eager to learn more about marine biology!
