Bony Fish Anatomy and Physiology Quiz

Living in Water - Chapter 4

• Aquatic life faces unique challenges, including buoyancy, movement through dense water, maintaining internal temperature differences from water, and coping with varying oxygen availabilities.
• Maintaining internal environment stability is difficult due to constant water and ion movement.
• Water's high density presents challenges for movement.
• Heat loss from water is significant.
• Ammonia is readily soluble in water, which is a positive aspect, but oxygen levels are often lower.

Physical Properties of Water and Air

• Water is significantly denser than air (about 833 times).
• Water is more viscous than air (about 55 times).
• It takes substantially more energy (about 3,500 times) to increase water temperature than air by the same amount at the same volume and quantity.
• Heat transfers approximately 25 times faster in water compared to air.
• Oxygen content is significantly lower in water than in air (around 6 mL/L in water versus 209 mL/L in air).
• Oxygen diffuses approximately 8,500 times faster in air versus water.
• Sound travels approximately 4.3 times faster in water compared to air.
• Water's refractive index is similar to that of the cornea.

Gills and Oxygen Uptake

• Gill structure facilitates unidirectional water flow for efficient oxygen uptake.
• Fish use buccopharyngeal pumping to move water unidirectionally through the gills.
• Opereucla and mouth flaps prevent water backflow into the mouth.
• Gill filaments and lamellae are sites of gaseous exchange.
• Secondary lamellae enhance gas exchange surface area.
• Ram ventilation is a strategy to obtain oxygen
• Countercurrent exchange maximizes oxygen uptake. Afferent blood vessels and water move in opposite directions.

Oxygen from Air

• Some fish adapt to low dissolved oxygen by obtaining oxygen from air.
• Betta fish use a labyrinth for air breathing.
• Electric eels periodically surface to breathe.
• Lungfish have lungs that originated from the swim bladder.
• Lungfish use burrow and mucous production for dormancy.

Adjusting Buoyancy in Bony Fish

• Most bony fish are neutrally buoyant, having similar densities to water.
• The gas bladder, an internal organ, helps achieve buoyancy.
• Fish adjust gas bladder volume by adding/removing gas to maintain neutral buoyancy as they navigate depth.

Buoyancy in Deep-Sea Fish

• Many deep-sea fish have modified swim bladders with lightweight compounds.
• Some deep-sea species have reduced or lost their swim bladder, adapting to use body fats for buoyancy.
• Length and location of rete mirabile and presence of a gas gland may vary between deep-sea species.

Aquatic Vision

• Aquatic vertebrates have spherical lenses that adjust position to focus on light.
• Terrestrial vertebrates use a flatter lens and a cornea to focus light.
• Water's refractive index is nearly similar to that of the cornea , so vision is less clear underwater.

Hearing in Water

• Sound travels about four times faster in water than in air.
• Solid objects reflect underwater sound.
• Sound is absorbed by vegetation in water.
• Inverse square law affects sound energy propagation.
• Thermoclines create channels for concentrated sound in open water.

Chemosensation: Taste and Smell

• Taste buds are present throughout the head and mouth area.
• Olfactory organs are located around the snout, for detection of dissolved substances.
• Sharks have exceptional sensitivity to low concentrations of odors.
• Salmon use permanently imprinted chemical signatures to locate home streams.

Lateral Line System

• The lateral line system detects water displacement (vibration) in aquatic vertebrates.
• The lateral line system consists of neuromast organs containing hair cells.
• These organs are in canals running along the body helping fish detect water currents or vibrations from prey, predators, and mates.
• Water movement causes cupula bending, exciting sensory cells in the neuromast to indicate direction and intensity of movement.
• Schooling fish use this system for maintaining spacing and recognizing their neighbors.

Electrical Discharge

• Some fish generate electric fields for communication, navigation predator avoidance.
• Electric fields are produced by special modified muscle or nerve cells.
• Strength of shock varies by species and location on fish.

Electroreception

• Sensitive electroreceptors, the Ampullae of Lorenzini, detect weak electrical signals from prey muscle contractions.
• Sharks and rays use these receptors to locate prey via detecting electrical signals.
• Electroreception is also found in some monotremes.

Nitrogen Excretion

• Animal groups excrete nitrogenous waste such as ammonia, urea or uric acid in differing ways.
• Bony fishes excrete ammonia through skin and gills.
• Mammals excrete primarily urea.
• Reptiles and birds have a more energy-intensive method of excretion: uric acid.

Vertebrate Kidneys

• Vertebrate kidneys remove excess water and waste chemicals from the body in the form of urine.
• Blood is filtered through glomeruli within nephrons.
• Nephons filter water, amino acids, and glucose and separate them into the form of urine for excretion.
• Urine formation occurs in several steps within the kidney.

Stenohaline vs Euryhaline

• Stenohaline fishes are restricted to either freshwater or saltwater and are less tolerant to changes in salinity.
• Euryhaline fishes, in contrast, can move between environments with different salinity levels and have greater tolerance.

Water and Salt Regulation - Freshwater Fish

• Freshwater fish gain water via osmosis and lose salts through diffusion.
• In order to counteract this they actively absorb sodium ions.
• Kidneys produce copious amounts of dilute urine to avoid excess water retention.

Water and Salt Regulation - Marine Fish

• Marine fishes lose water by osmosis and gain sodium and chloride via diffusion.
• Marine fishes actively absorb salt through osmosis and drink seawater to maintain salt balance.
• Kidneys excrete a small volume of concentrated urine.