FISH 300 Midterm #2

Osteology

Scientific study of bones and skeletal structures.

Vertebrae

Bones / cartilaginous segments that make up the backbone.

Premaxilla

Superficial paired dermal bones located at the front tip of the upper jaw. (bony fish)

Maxilla

A paired bone that forms the major part of the upper jaw. (bony fish)

Dentary

Largest most anterior dermal bone making up the mandible (lower jaw)

Myology

The study of the muscular system

Myocytes

Muscle cells

Myomere

W or V-shaped blocks of skeletal muscle tissue found along the trunk of fish and other aquatic chordates (fillets)

Adductors

Muscles used to bring to body.

Abductors

Muscles used to pull away from body.

Protrusibility

The ability of the upper and lower jaws to thrust or extend outward from the head during feeding.

Aerobic (red muscle)

For sustained swimming, less strength + pursuit

Anaerobic (white muscle)

For “burst” swimming, high strength + ambush

Gill Rakers

For retention; there to make sure food doesn’t slip through gill opening.

Pharyngeal Teeth

Secondary set of teeth used for mastication (chewing).

Pyloric Caeca

Finger like pouch located at the junction of the stomach and anterior intestine; maybe used for nutrient absorption, storage.

Spiral Valve Intestines

Slows down digestion to maximize extraction of energy and nutrients

Herbivore

Primarily eat plants, algae, and seagrass.

Carnivore

Primarily eat other animals like smaller fish, crustaceans and worm.

Gelativore

Primarily eat gelatinous zooplankton such as jellyfish.

Erythrocyte

Red blood cell that contains hemoglobin and circulates through the body to transport oxygen and carbon dioxide.

Artery

A blood vessel that carries blood away from the heart toward the gills and the rest of the body.

Vein

A blood vessel that collects deoxygenated blood from the body tissue and organs and carries it back toward the heart.

Gill Arch

Curved bony or cartilaginous skeletal support rid located in the pharynx of fish.

Gill Filaments

Thin, feather-like structure attached in two alternating rows to the bony or cartilaginous giil arch. Where oxygen uptake/CO2 release happen.

Gill Lamellae

Tiny, plate-like folds on fish gills where gas exchange takes place

Operculum

The hard, bony flap on the side of the head that covers and protects the gills.

Buccal Pump

1. Opens mouth, operculum closes

2. Gill cavity expansion

3. Mouth closes, operculum opens

4. Gill cavity contracts

Used to draw in water and push it across the gills for gas exchange.

Counter Current Exchange

A process in fish gills where water flows over the gill lamellae in the opposite direction of blood flow. This maintains a concentration gradient, allowing oxygen to continuously diffuse from the water into the blood while carbon dioxide diffuses out.

RAM Ventilation

A method of respiration in which fish swim forward with their mouths open, forcing oxygen-rich water to flow continuously over their gills. This allows them to extract oxygen from the water without actively pumping it through their gills.

Spiracle

A small opening located behind the eyes of some fish, particularly sharks and rays, that allows water to enter the gills for respiration without passing through the mouth.

Osmosis

Diffusion of water through a semi-permeable membrane.

Osmoregulation

The process by which fish maintain the proper balance of water and salts in their bodies despite differences in salt concentration between their body fluids and the surrounding environment.

Osmoconformer

An organism maintains an internal osmotic concentration similar to its environment, minimizing water loss or gain. Does not go through osmoregulation.

Example: Sharks and kin use trimethylamine oxide to counter toxic effects or urine in their tissue.

Osmoregulation (Fresh Water)

Hyperosmotic to their environment, meaning their body fluids have a higher concentration of dissolved substances than the surrounding water. They must eliminate excess water while conserving and absorbing salts.

Osmoregulation (Salt Water)

Hypo-osmotic to their environment, meaning their body fluids have a lower concentration of dissolved substances than the surrounding seawater. They must conserve water while eliminating excess salts.

Buoyancy

The quality of being able to float.

Swim Bladder

A gas-filled organ found in many bony fish that regulates buoyancy, allowing fish to maintain their position in the water column without constantly swimming.

Swim Bladder (Primative)

Have a swim bladder connected to the digestive tract by a pneumatic duct, allowing them to gulp air at the surface or release gas through their mouths to regulate buoyancy.

Swim Bladder

Have a swim bladder that is not connected to the digestive tract. Instead, they regulate buoyancy by adding or removing gas through specialized structures associated with blood vessels.

Barotrauma

Pressure stress from rapid ascent (advanced fish only)

Olfaction

The sense of smell that allows fish to detect chemicals dissolved in water using specialized sensory receptors in their nostrils (nares). Fish use olfaction to locate food, detect predators, find mates, and navigate their environment.

Gustation

The sense of taste that allows fish to detect chemicals dissolved in water or present in food using specialized taste buds. Fish use gustation to identify food, determine if something is edible, and locate food in their environment.

Nasal Rosette

A structure inside the nasal cavity with folded olfactory lamellae that increase surface area for detecting chemicals in water, improving the fish’s sense of smell.

Barbels

Whisker-like sensory structures near a fish’s mouth that contain taste buds and other sensory receptors. They help fish locate food, especially in murky or low-visibility water.

Acuity

The ability of a fish to detect and distinguish between different odors or chemicals dissolved in water, even at very low concentrations.

Pheromones

Chemical signals released by fish into the water that influence the behavior or physiology of other fish of the same species. They are used for communication, attracting mates, reproduction, and signaling danger.

Sexual Dimorphism

Physical differences between males and females of the same species, such as differences in size, coloration, body shape, or fin structures. These differences often relate to reproduction and mate selection.

Photoreception

The ability to detect light using specialized photoreceptor cells (rods and cones) in the eyes. It allows fish to perceive light, color, movement, and their surroundings.

Pineal Eye

A light-sensitive structure associated with the pineal organ that detects changes in light and darkness. It helps regulate biological rhythms, such as sleep-wake cycles and seasonal reproductive activity.

Rods

Detect light in dim conditions and help with night vision.

Cones

Detect colors and fine details in brighter light.

Tapetum Lucidum

Adaption for dim lighting; silver, reflective lining behind retina to multiply light reflection.

Pupillary Operculum

Adaption for bright lighting; an extension of the iris

Otolith

Small calcium carbonate structures (ear stones) found in the inner ear of bony fish that help detect sound, gravity, and movement, allowing fish to maintain balance and orientation.

Sagitta

Largest of the three pairs of otoliths (ear stones) in most bony fish. It helps detect sound and is commonly used by fisheries scientists to determine a fish's age.

Semicircular Canals

Three fluid-filled canals in the inner ear that detect rotational movement of the head, helping fish maintain balance, orientation, and coordination while swimming.

Pitch

The upward or downward rotation of a fish's head around its side-to-side axis, allowing it to tilt its body nose-up or nose-down while swimming.

Roll

The rotation of a fish's body around its head-to-tail axis, causing it to tilt or turn sideways while swimming.

Yaw

The rotation of a fish's head and body left or right around its vertical axis, allowing it to change direction while swimming.

Advantages of Protruding Jaw

1. Increased Suction

2. Improved Prey Capture

Jaw Teeth

Located on the upper and lower jaws. Used to grab, hold, and tear prey.

Gill Raker Teeth

Located on the gill arches. Help trap food, filter particles, and prevent prey from escaping through the gills.

Pharyngeal Teeth

Located in the pharynx (throat). Used to crush, grind, and break down food before swallowing.

Intestine Length in Bony Fish (Carnivores)

Short

Intestine Length in Bony Fish (Herbivores)

Long

Intestine Length in Bony Fish (Omnivore)

Medium

Countercurrent Exchange

Water and blood flow in opposite directions across the gills, allowing fish to absorb more oxygen (up to about 80–90%).

Concurrent Exchange

Water and blood flow in the same direction across the gills, making oxygen exchange less efficient (theoretical maximum of about 50%).