Final Exam Study Guide Marine Biology 2025-26: Seabirds, Marine Mammals, Estuaries, and Coral Reefs

Flashcards covering thermoregulation, marine mammal classifications, seabird orders, estuarine circulation, seafloor biology, polar adaptations, and coral reef ecology.

Thermoregulation

Muscle contractions that are exothermic and evaporate as a result of heat loss.

Countercurrent heat exchange

A process where blood flows in the opposite direction via the arteries, allowing heat from warm blood to be absorbed by cooler blood in surrounding veins before it is lost in appendages.

Class Mammalia

A class of animals including humans, bears, and walruses characterized by mammary glands, hair/fur, live birth, a four-chambered heart, and a diaphragm.

Class Sirenia

A group of herbivores consisting of manatees, dugongs, and sea cows that have no pelvic limbs, long intestines, and specialized teeth for chewing plants.

Cetaceans

Dolphins and whales that breathe through dorsal blowholes, lack body hair/appendages, and use horizontal flukes for propulsion.

Seasonal delayed implantation

An adaptation in elephant seals where the zygote undergoes divisions to become a blastocyst and remains inactive until the time is right for development and birth.

Echolocation

Clicks produced by the melon, a large organ in the head of cetaceans, used for communication and navigation.

Unihemispheric slow wave sleep

A sleeping method where cetaceans sleep with half of their brain to continuously breathe and swim.

Diving reflex

Physiological responses including breathing cessation, bracycardia, vascoconstriction, muscle oxygen depletion, lactate accumulation, and blood chemistry changes.

Balaenopteridae

Baleen whales, including blue, fin, and humpback whales, that use grooves in their mouths for engulfment feeding or perform bubble-net feeding.

Orcas

Also known as killer whales; they are odontocetes with broad geographic ranges that live in pods with direct female descendants and consistently attack other marine mammals.

Alloparenting

The shared responsibility of offspring, as observed in bottlenose dolphins.

Lanugo

A temporary coat shed by pinniped pups (walruses, seals, and sea lions) shortly after birth.

Sexual dimorphism

An obvious change in size, appearance, and behavior between adult males and females, often used to attract and rear young.

Sphenisciforms

About 18 types of penguins in the Southern Hemisphere that use wings for diving and go ashore to breed.

Procellariiforms

Albatrosses, petrels, and shearwaters that spend most of their time above the surface, have stomach oil reserves, and produce eggs less sensitive to chilling.

Pelecaniforms

A group consisting of pelicans, boobies, and gannets that capture prey via plunge diving.

Charadriiforms

Gulls, terns, puffins, and sandpipers that use subsurface pursuit diving and rely heavily on the sea for food.

Coastal plain estuaries

Broad or shallow embayments formed from deeper V-shaped channels and flooded river mouths following continental glaciation.

Vertically mixed estuary

An estuary with equal salinity and water density from the surface downward at any given location.

Salt wedge

A circulation pattern where fresh water stays on top and saltwater remains on the bottom.

Isohalines

Lines of equal salinity plotted to classify estuaries by mixing patterns and to understand organism distribution.

Flushing time

The time it takes for water in an estuary to be replaced, influencing nutrient transport and the fate of pollutants.

Epifauna

Animals that crawl on or are attached to the surface of the sea bottom.

Infauna

Benthic animals that live within the substrate forming the ocean bottom.

Meiofauna

An infauna that is intermediate in size between macroscopic (macro) and microscopic (micro) fauna.

Wrack line

Seaweed washed up on the sand that provides food for terrestrial organisms or marine amphipods.

Biochemical Oxygen Demand (BOD)

Oxygen demand created when excessive nutrients cause phytoplankton blooms to die, which can lead to dead zones.

DDT

A pesticide available since 1945 that bioaccumulates, is insoluble in water, and interferes with calcium disposition in eggshells.

Abyssal zone

The seafloor and ocean bottom areas located from $3,000\,m$ to $6,000\,m$ deep.

Hadal zone

The deepest part of the ocean, starting at $6,000\,m$.

Photophores

Light producing organs found on various marine animals.

Diurnal vertical migration

Daily movement that allows animals to feed on pelagic sources at night and lower their metabolic rate in deeper, cooler water.

Magnetoreception

The use of the Earth's magnetic field to orient and navigate.

Deposit feeding

The process of engulfing sediments through digestive tracts to extract nourishment from organic material.

Absorptive feeding

A feeding method where nutrients are extracted via digestive processes occurring outside the body.

Stability-time hypothesis

The theory that stable conditions lead to specialized adaptations while unpredictable environments favor a wide range of tolerance.

Riftia

A large red worm found in hydrothermal vent communities that lacks a digestive tract and uses a sulfide-binding protein and endosymbionts in a trophosome.

Thermohaline circulation

Ocean circulation driven by the sinking of dense salty water (sea ice formation) and replacement by warmer freshwater, mixing nutrients.

Notothenoids

Cold-water fish found in polar seas that adapted when other species faced extinction.

Zooxanthellae

Unicellular algae that live in mutualistic, symbiotic relationships with hermatypic (reef-building) corals.

Atolls

Ring-shaped reefs from which a few islands project above the sea surface.

Ocean acidification

A result of atmospheric $CO_2$ reacting with ocean water to form carbonic acid, which decreases the ocean pH.