Sp25 BIOL D013 02Y Marine Biology Lecture Exam #3/Lab Exam #3

What are tetrapods?

Vertebrates with four limbs (includes reptiles, birds, mammals). Marine groups: turtles, snakes, crocodiles, seals, whales, seabirds.

Class, phylum, subphylum for reptiles?

Class Reptilia, Phylum Chordata, Subphylum Vertebrata.

Define ectotherm.

Rely on external heat sources (e.g., marine reptiles).

Major evolutionary advancement in reptiles?

Amniotic egg (allows reproduction on land).

How many sea turtle species exist?

7 species (e.g., Leatherback: largest, no hard shell; Green: herbivorous; Hawksbill: eats sponges).

How is sex determined in sea turtle eggs?

Temperature-dependent (warmer = females).

How do female turtles return to their birthplace?

Magnetoreception (detect Earth's magnetic fields).

Characteristics of sea snakes?

Laterally flattened tails, venomous, give live birth.

Only reptile with a 4-chambered heart?

Crocodiles (closely related to birds).

How do marine reptiles/birds handle salt?

Salt glands (excrete excess salt).

Seabird groups and examples?

- Probers/gleaners (shorebirds, e.g., sandpipers). - Surface feeders (e.g., gulls). - Pursuit divers (e.g., penguins). - Pursuit plungers (e.g., boobies). Most birds are NOT seabirds.

Define endothermic.

Maintain body temperature internally (birds and mammals).

Countercurrent vascular system?

Blood vessels in extremities minimize heat loss (e.g., bird legs, whale flippers).

Four orders of marine mammals?

- Cetacea (whales/dolphins). - Carnivora (seals, otters, polar bears). - Sirenia (manatees). - Pinnipedia (seals, sea lions, walrus).

Which order are strict vegetarians?

Sirenia (manatees, dugongs).

Organisms with flukes and blowholes?

Cetaceans. Largest animal: Blue whale.

Suborders of Cetacea?

- Odontoceti (toothed whales: echolocate, e.g., sperm whale). - Mysticeti (baleen whales: filter-feeders).

Adaptations for diving?

Bradycardia (slowed heart rate), vasoconstriction (reduce blood flow), high myoglobin (store oxygen).

What is echolocation?

Use of sound waves to navigate/hunt (toothed whales). Chemoreception ineffective underwater.

Define breaching, spyhopping, stranding.

- Breaching: Whales leap out of water (communication/parasite removal). - Spyhopping: Raise head vertically (observe surroundings). - Stranding: Beach themselves (illness/navigation errors).

What is an estuary?

Where rivers meet the sea; nurseries for marine life due to protection/nutrients.

Types of estuaries?

- Coastal plain (drowned river valleys, e.g., Chesapeake Bay). - Bar-built (sandbars, e.g., Outer Banks). - Tectonic (land subsidence, e.g., San Francisco Bay). - Fjords (glacier-carved, e.g., Norway).

Define brackish.

Mix of fresh/salt water. Saltier at depth (salt wedge).

Most common substrate?

Mud (anoxic due to poor oxygen flow).

Primary producers in estuaries?

Flowering plants (e.g., seagrasses, mangroves). Algae/plankton hindered by turbidity.

Euryhaline vs. stenohaline?

Euryhaline tolerates salinity changes (e.g., mussels); stenohaline does not (e.g., corals).

How do plants handle salinity?

Salt glands (expel salt) or concentrate solutes in tissues (e.g., pickleweed).

Key features of salt marshes?

Halophytic plants, submerged at high tide, provide detritus-based food. Found in temperate zones.

Key features of mangrove forests?

Pneumatophores (aerial roots for oxygen), found in tropics.

Phylum/class of corals?

Phylum Cnidaria, Class Anthozoa.

Soft body of coral?

Polyp (sits in corallite made of CaCO₃).

Hermatypic vs. ahermatypic?

Hermatypic = reef-building (with zooxanthellae); ahermatypic = non-reef-building.

Coral nutrition sources?

Zooxanthellae (photosynthesis), tentacles/nematocysts (prey capture), mucus nets.

Conditions for reef growth?

Warm (20-30°C), shallow (<50m), clear, low-nutrient water, hard substrate.

What is coral bleaching?

Expulsion of zooxanthellae due to stress (warming, pollution, UV).

Reef developmental stages (Darwin)?

Fringing reef → Barrier reef → Atoll.

Parts of a fringing reef?

Reef flat (exposed at low tide), reef crest (shallow edge), reef slope (highest coral cover).

How do atolls form?

Volcanic island sinks, leaving coral ring (fringing reef → barrier reef → atoll).

Why are reefs productive?

Zooxanthellae recycle nutrients; tropical waters are nutrient-poor.

Crown of Thorns sea star prey?

Corals.

Why are birds considered endothermic?

Birds maintain a constant internal body temperature regardless of the environment.

How do probers and gleaners obtain their food?

They feed by picking small prey from the surface of mud, sand, or vegetation.

Why is deeper water in estuaries saltier than surface water?

Dense saltwater sinks below lighter freshwater, forming a salt wedge.

What life stage do reef-building corals exhibit?

Reef-building corals only have a polyp stage in their life cycle.

Which part of the reef shows the highest coral growth?

The reef slope has the highest coral cover and growth due to optimal light and water flow.

Foot (mussel)

Muscular structure for movement.

Gills (mussel)

Respiration and food sorting.

Mantle (mussel)

Secretes shell internally.

Byssal threads (mussel)

Attach to substrates.

Pen (squid)

Internal shell (support).

Gill (squid)

Respiratory organ.

Aristotle's lantern (sea urchin)

Feeding structure (jaws/teeth).

Ambulacral groove (sea star)

Houses tube feet.

Ring canal (sea star)

Part of water vascular system.

Respiratory trees (sea cucumber)

Gas exchange organs.

Gill rakers (dogfish shark)

Filter food from water.

Spiral intestine (dogfish shark)

Increases nutrient absorption.

Swim bladder (perch)

Buoyancy control.