FIREBAC - quiz 1 - flashcard

What is the pelagos?

The water column of the ocean; organisms living or swimming in it belong to the pelagic environment.

What is the benthos?

The ocean bottom and the organisms associated with the seabed.

What is plankton?

Organisms that drift mainly with currents and cannot determine their large-scale horizontal displacement, even though some can swim actively, especially vertically.

What is nekton?

Pelagic organisms capable of active swimming independently of currents, including swimming against a current.

What is the main difference between plankton and nekton?

Plankton cannot determine their large-scale horizontal displacement and mainly drift with currents, whereas nekton can actively swim independently of currents.

What is the euphotic zone?

The upper water layer receiving enough light for photosynthesis; in the lecture it is rarely deeper than about 100 m.

What is the disphotic zone?

A zone with a small but measurable amount of light, insufficient for photosynthesis.

What is the aphotic zone?

The zone where light is absent; the lecture places it below about 1000 m.

What basic physical problem do pelagic nekton face in the water column?

They must avoid sinking, either by increasing buoyancy or by continually swimming.

What are the three main nekton groups presented in the lecture?

Chordates, molluscs and some arthropods.

What are Chondrichthyes?

Cartilaginous fishes such as sharks and rays.

What are Osteichthyes?

Bony fishes whose skeleton is primarily composed of bone tissue.

What type of skeleton do Chondrichthyes have?

A skeleton made primarily of cartilage.

What type of skeleton do Osteichthyes have?

A skeleton made primarily of bone.

How do the gills of Chondrichthyes and Osteichthyes differ?

Chondrichthyes generally have exposed gill slits, whereas Osteichthyes have gills covered by an operculum.

Which major fish group lacks a swim bladder?

Chondrichthyes, the cartilaginous fishes.

How does fertilisation generally differ between Chondrichthyes and Osteichthyes?

Chondrichthyes have internal fertilisation, whereas fertilisation is mostly external in Osteichthyes.

What are the main groups of marine mammals presented in the lecture?

Cetaceans, Pinnipeds, Sirenia and Ursids.

What are Mysticetes?

Baleen whales.

What are Odontocetes?

Toothed whales.

Why is it useful to remember the term Odontocetes?

Odontocetes use echolocation, which appears later as an important sensory adaptation.

What are the three main pinniped families presented in the lecture?

Phocidae (seals), Otariidae (sea lions) and Odobenidae (walrus).

What animals belong to Sirenia?

Manatees and dugongs.

What characteristics of mammals are retained by marine mammals?

They regulate body temperature, feed their young milk, and have fur at some point in their life history.

What marine reptile groups are mentioned in the lecture?

Sea turtles, sea snakes, marine crocodiles and marine iguanas/lizards.

Why are amphibians poorly suited to fully marine life?

Their highly permeable skin and limited seawater osmoregulatory capacity make it difficult to prevent water loss and maintain ion balance in salty water.

What adaptations help marine birds deal with life at sea?

Wax and fat on feathers provide waterproofing and insulation, while salt glands remove excess salt from the blood.

What do salt glands do in marine birds?

They remove excess salt from the blood, allowing concentrated salt to be expelled through the nasal region.

What is the main difference between penguins and auks regarding flight?

Penguins have lost flight and use their wings as flippers, whereas auks retain the ability to fly.

Where are penguins and auks primarily found?

Penguins are associated with the Southern Hemisphere, whereas auks occur in the Northern Hemisphere.

Why do auks and penguins look similar despite not being closely related?

Convergent evolution: similar ecological pressures independently produced similar adaptations.

What provides insulation and energy storage in penguins?

Fat and trapped air.

What are important adaptations of cephalopods mentioned in the lecture?

A powerful beak, mantle and siphon for movement, and an ink gland used to confuse predators.

How does jet propulsion work in cephalopods?

Water is forcefully expelled through the siphon, pushing the animal in the opposite direction.

What is a detritivore?

An organism that feeds on dead organic matter or detritus.

What is a herbivore?

An organism that feeds on plant material such as phytoplankton, macroalgae or plants.

What is a carnivore?

An organism that feeds on animals such as fish or zooplankton.

What is an omnivore?

An organism that consumes food from both plant and animal sources.

What does euryphagous mean?

Having a broad dietary niche and consuming many types of food.

What does stenophagous mean?

Having a restricted dietary niche and consuming a limited range of foods.

What does monophagous mean?

Feeding essentially on one type of food.

Can a fish be both carnivorous and euryphagous?

Yes. Carnivorous describes what it eats, whereas euryphagous describes how diverse its diet is.

What two ecological functions are strongly related to fish body form?

Locomotion type and feeding ecology.

What body form is typical of rover predators?

A long, streamlined or torpedo-shaped body suited to efficient forward swimming.

What is the advantage of a streamlined fish body?

It reduces resistance and supports efficient forward swimming.

What does an upward-facing mouth suggest about a fish's feeding ecology?

It suggests that the fish is adapted to capture prey near the water surface.

What are the locomotor characteristics of deep-bodied fish?

Their laterally flattened bodies provide excellent manoeuvrability, but they are not adapted for prolonged fast swimming.

What is the advantage of an eel-like body shape?

It allows movement through crevices and restricted spaces, as in moray eels.

Why do herbivorous and detritivorous fishes generally have long digestive tracts?

Plant and detrital material can be difficult to digest, so a long gut provides more processing time and surface area.

How long can the gut of herbivorous or detritivorous fish be according to the lecture?

Up to about 15 times body length.

Why do carnivorous fishes generally have shorter digestive tracts?

Animal tissue is generally more readily digestible and requires less processing than plant or detrital material.

What is ram feeding?

The predator moves toward the prey with its mouth open, engulfing the prey together with water.

What is suction feeding?

The fish rapidly expands its buccal cavity, reducing pressure so that water and prey are drawn into the mouth.

What causes prey to enter the mouth during suction feeding?

Rapid expansion of the buccal cavity lowers pressure inside the mouth, causing water to rush inward and carry the prey with it.

What is manipulation feeding?

Direct use of the jaws or teeth to grasp, bite, tear, scrape or crush food.

How can ram and suction feeding be remembered simply?

Ram: fish moves toward prey. Suction: prey is drawn toward fish.

How does a swimming fish generate forward thrust?

Muscular waves travel from head to tail and the body and fins accelerate water backward; the reaction force pushes the fish forward.

What happens to lateral forces during normal fish propulsion?

They largely cancel each other, leaving a net force that produces forward movement.

What is buoyancy?

The tendency of an organism to float or remain suspended rather than sink.

What factors affecting fish buoyancy are identified in the lecture?

Body composition, especially lipids; water density and salinity; swim bladder and gas regulation; and body or fin morphology producing dynamic lift.

What is a swim bladder?

An internal gas-filled organ used by many bony fishes to regulate buoyancy.

What is a physostomous fish?

A fish that can regulate its swim bladder by gulping atmospheric air.

What is a physoclistous fish?

A fish in which swim-bladder gas is regulated through the bloodstream rather than by gulping atmospheric air.

How does increasing gas in a swim bladder affect buoyancy?

It increases buoyancy, making it easier for the fish to remain higher in the water column.

How does decreasing gas in a swim bladder affect buoyancy?

It decreases buoyancy, making descent easier.

How can sharks maintain lift without a swim bladder?

They use adaptations including body composition, streamlined morphology, a muscular tail, paired fins and hydrodynamic lift while swimming.

What is homeostasis?

The maintenance of relatively stable internal conditions despite changes or challenges in the external environment.

What is osmoregulation?

The maintenance of the appropriate water and ion balance of body fluids.

How are homeostasis and osmoregulation related?

Osmoregulation is one form of homeostasis because it keeps internal water and ion conditions relatively stable.

What is osmosis?

The passive movement of water across a membrane toward the side with the higher concentration of dissolved solutes.

In simplified terms, in which direction does water move during osmosis?

From the less concentrated or less salty side toward the more concentrated or saltier side.

What osmotic problem does a freshwater fish face?

Its body fluids are more concentrated than the surrounding freshwater, so water tends to enter its body while ions tend to be lost.

How does a freshwater fish compensate for its osmotic problem?

It must eliminate excess water and actively retain or acquire ions.

What osmotic problem does a marine fish face?

Seawater is more concentrated than its body fluids, so water tends to leave its body and salt balance is challenged.

How does a marine fish compensate for its osmotic problem?

It must conserve or replace lost water and regulate excess ions.

What makes secondary gill lamellae effective gas-exchange surfaces?

They provide a very large surface area, a very thin diffusion barrier and a dense capillary supply.

In which direction does oxygen diffuse across fish gills?

From the water into the blood.

In which direction does carbon dioxide diffuse across fish gills?

From the blood into the water.

How do water and blood flow relative to one another across fish gills?

They flow in opposite directions.

Why is countercurrent flow at the gills efficient?

Opposite flow maintains an oxygen concentration gradient along the exchange surface, allowing oxygen to continue diffusing from water into blood.

What would happen if water and blood flowed in the same direction at the gills?

Their oxygen concentrations would progressively approach equilibrium, reducing the diffusion gradient and making oxygen extraction less efficient.

What is a regional endotherm?

An animal capable of keeping particular tissues or body regions warmer than the surrounding environment rather than maintaining the entire body at one elevated temperature.

How do muscles contribute to temperature control in regional endothermic fish?

Active muscles generate metabolic heat that is carried by the blood.

What is the role of the rete mirabile in regional endothermy?

It allows heat from warm blood leaving the muscles to transfer to colder incoming blood, recovering heat before it is lost to the environment.

What is the difference between countercurrent exchange at the gills and in the rete mirabile?

At the gills, countercurrent flow improves gas exchange; in the rete mirabile, countercurrent flow conserves and transfers heat.

What is the lateral line?

A sensory system containing mechanoreceptors that detect water movements and vibrations.

What is the lateral line used for?

Spatial awareness and perception of approaching stimuli such as predators.

Which marine mammals use echolocation?

Odontocetes, or toothed whales.

What is echolocation?

The use of emitted sound waves and their returning echoes to obtain information about the surroundings.

What roles do the melon and lower jaw have in odontocete echolocation?

The melon is associated with sound emission/channeling, while the lower jaw is associated with reception.

What are the Ampullae of Lorenzini?

Jelly-filled electroreceptor pores in cartilaginous fishes that can detect electromagnetic fields and possibly temperature gradients.

How can electroreception help a shark find prey?

It can detect electrical fields associated with animal muscle activity.

How may electroreception contribute to navigation?

It may allow detection of information associated with the Earth's geomagnetic field.

What functions of vision are highlighted in the lecture?

Early predator detection, camouflage and mimicry, ocelli or eye spots, schooling behaviour and specialised visual adaptations.

How can schooling reduce predation risk?

Individuals within a school are less vulnerable than isolated fish; the lecture notes that fish leaving the school are attacked successfully.

What additional energetic advantage can schooling provide?

It may reduce drag and lower the energetic cost of swimming.

What is countershading?

A camouflage pattern in which the dorsal surface is dark and the ventral surface is light.

Why does countershading provide camouflage when a fish is viewed from above?

The dark dorsal surface blends with the darker water or depth below.

Why does countershading provide camouflage when a fish is viewed from below?

The light ventral surface blends with the brighter surface light above.

What are the two major reasons for migration emphasized in the lecture?

Feeding and reproduction.