BIO224 Ichthyology Flashcards

Flashcards covering key vocabulary

How many Extant Fish Species

Approximately 35,800

Epipelagic Zone

Ocean zone from the surface to 200m.

Mesopelagic Zone

Ocean zone from 200m to 1,000m.

Bathypelagic Zone

Ocean zone from 1,000m to 4,000m.

Abyssopelagic Zone

Ocean zone from 4,000m to 6,000m.

Hadalpelagic Zone

Ocean zone below 6,000m.

What does hydrostatic pressure effect at deep depths

Protein formation.

Tri-methylamine N-oxide (TMAO)

Stabilises proteins in fish tissues, concentration increases with depth.

Paraphyletic

Common ancestor in group but not all descendents are in the group.

Agnatha

Jawless vertebrates.

Class Petromyzontida

Lampreys; most extinct, 48 extant spp.

Class Myxini

Hagfish; most extinct, 91 extant spp.

Anadromy (anadromous)

Adult life in sea, returning to freshwater to breed.

Diadromy (diadromous)

Migration between freshwater and seawater. The principal feeding and growing biome differs from the reproductive biome.

Catadromy (catadromous)

Fish that live in freshwater and return to the sea to breed.

Gnathostome

Jaws

Mandibular arch

Becomes biting jaws

Class Chondrichthyes

Cartilaginous fish, including sharks, skates, rays, and chimaeras.

Sub-class Elasmobranchii

Sharks, Skates, Rays (1,283* extant spp.)

Class Osteichthyes

Bony Fish (34,344* extant spp.)

Chondrichthyes Characteristics

Cartilaginous fish, Spiracle, No operculum opening, No swim bladder, Ampullae of Lorenzini, Spiral valve, Placoid scales (denticles), Internal fertilization.

Osteichthyes Characteristics

Bony Fish, No spiracle, Operculum covers gills, Swim bladder, No electro receptors, No spiral valve but pyloric caecae, Overlapping scales, Mostly broadcast spawners.

Lower teleosts Characteristics

Soft fin rays, 1 dorsal fin (maybe adipose), Pectoral fins low, Pectoral fin base horizontal, Pelvic fins abdominal, Pelvic fins with numerous rays, Scales usually cycloid, Swimbladder often physostomatous

Higher teleosts Characteristics

May also have spiny fin rays, 1 or more dorsal fins, Pectoral fins higher, Pectoral fin base angled towards vertical, Pelvic fins thoracic or jugular, Pelvics fins with reduced number of rays, Scales usually ctenoid, Swimbladder physoclistous

What percent of all fish are teleosts

96%

What are the “big seven” fish families by species count?

Cyprinidae, Gobiidae, Characidae, Cichlidae, Labridae, Loricariidae, Serranidae

What is the largest vertebrate order?

Perciformes

Which family is known for fused pelvic fins forming an adhesive disc?

Gobiidae

What is a “species flock”?

A group of closely related species derived from a common ancestor, often in isolated habitats like African Great Lakes.

what is the Characidae family

characins, piranha

What is the Cyprinidae family

minnows, carps - largest fish family

what is the Gobiddae family

gobies

what is the Cichildae family

cichlids

what is the Labridae family

Wrasses

what is the Loricariidae family

armoured catfish

what is the family Serranidae

groupers

What are clupieformes

herrings, sardines, shads, menhaden, anchovies - very important commercially

What are Gadiformes

cod, haddock, pollock, whiting - very important commercially

what is a physostome

a type of fish with a swim bladder connected to the gut, allowing for gulping air.

what is a physoclist

a type of fish with a closed swim bladder that is not connected to the gut, regulating buoyancy through gas exchange.

What is the Bohr effect

Describes a reduction in haemoglobin-oxygen affinity under lower pH

what is the Root effect

Describes a reduction in the oxygen carrying capacity of hemoglobin at low pH, specifically in some fish species.

what is the primary function of the caudal fin

provides thrust and propulsion for swimming.

what is the difference between median and paired fins

Median fins - Dorsal, aal, caudal

Paired fins - pectoral, pelvic

what tail is best for short bursts of speed and has high drag

low aspect ratio tails. e.g. rounded, truncate (sole, flatfish)

what type of tail is best sustained for swimming and has low drag

high aspect ration tails. e.g. forked lunate (tuna)

what is the aspect ration of a tail

Aspect Ratio = (Tail height) squared / Tail area

what is a myotome

a segment of axial muscle (contracts to generate flexion)

what is the function of red muscle

slow, continuous swimming (long durations)

what is the function of white muscle

Fast, powerful bursts (used briefly)

What is Body Caudal Fin Swimming (BCF)

swimming powered by side to side movements

What is Labriform swimming

Swimming using pectoral Fins (wrasses, parrot fish)

what’s the ideal body shape for continuous swimming

Fusiform (streamlined)

what do fillets in scombroids do

improve hydrodynamic efficiency

Which fin types help prevent pitch, roll and yaw

pitch - pectorals and pelvics

roll and yaw - dorsal and anal

what is buoyancy

a force exerted by a fluid that opposes an objects weight

what does archimedes principle state

the submerged weight of fish = difference between fish weight and the water is displaces

2 main strategies fish evolved to increase buoyancy

1 - reducing dense body parts

2 - using buoyancy aids (lipids/gas)

what is the specific gravity of seawater, fish muscle and bone

• Seawater: 1.026

• Fish muscle: 1.050

• Bone: 2.000

what is dynamic lift

lift generated by movement (e.g. pectoral fins in sharks)

what is static lift

buoyancy provided by low-density substances e.g. lipids/gas

what is a major lipid used by elasmobranchs for buoyancy

Squalene (~0.86)

what law explains how gas volume changes with depth

Boyles Law

what are the two types of gas bladders

physostomous - bladder connected via pneumatic duct

physoclistous - duct closes; uses gas gland and rate mirabile

what is the function of the gas gland

secretes lactic acid, lowers pH and causes oxygen to dissociate from haemoglobin

what is the rate miracle

a counter current capillary system (helps inflate swim bladder)

What physiological effects help release O₂ into the bladder?

• Bohr effect: Lower pH reduces Hb-O₂ affinity

• Root effect: Reduces total O₂ carrying capacity

• Salting out & CO₂ effects also reduce solubility and O₂ binding

why might deep-sea fish have multiple gas glands and long rete mirabile

to increase oxygen multiplication at high pressures for buoyancy control

why do some fish (scombroids) lose their swim bladder

to allow rapid vertical movement and avoid sonar detection by predators

what are two main steps in fish respiration

ventilation (moving water to gills) and extraction (taking oxygen from water)

what are the functions of gills

• gas exchange

• osmoregulation

• acid-base balance

• excretion of nitrogenous waste

structure of gill

• gill arch

• gill rakers

• gill filaments with lamellae

what are two main types of ventilation

Ram ventilation (swimming forces water over gills)

Buccal ventilation (muscular pumping of water)

what adaptation do ram ventilation fish like tuna have

Gill fusions to improve efficiency

where do fish have rete mirabile

• swim bladder

• red muscle

• retina

what is rete mirable

a counter current capillary system (helps to multiply gas/heat)

what is the role of the choroid gland

maintains high oxygen levels in the retina via the rete mirabile

what is a tapetum lucidum

a reflective layer behind the retina that enhances vision in low light

what are tubular eyes

fixed cylindrical eye adapted for upward, binocular vision (deep sea fish)

what is a neuromast

a sensory organ in the lateral line that detects water movement

what are otoliths used for

balance, hearing (aging fish)

what fish structure can amplify sound

swim bladder

what are ampullae of lorenzini

specialised electroreceptors in elasmobranchs and some teleosts used to detect electric currents

what are the two types of colour in fish

bio chromes - pigment based

schematochromes - structural, reflective

what hormones regulate physiological colour change

Melanin concentration hormone (MCH)

a-Melanocyte Stimulating Hormone (a-MSH)

what is disruptive colouration (silvering)

patterns like stripes/bars that break up the fish’s outline and confuse predators

what is facultative mimicry

ability to change colour/pattern to mimic multiple species

the two main sources of bioluminescence are …

symbiotic bacteria and self-luminous (photophores)

how do deep-sea fish use red light

produce and see red light to hunt prey like crustaceans

what is homeostasis

maintaining a stable environment including water and salt balance

what is osmoregulation

active regulation of water and ion concentrations to maintain internal balance

what is osmosis

movement of water across a semi permeable membrane due to solute concentration differences

what’s the difference between hyper osmotic and hyposmotic

hyper - fish is more concentrated than environment (water enters)

hypo - fish is less concentrated than environment (water leaves)

how do elasmobranchs osmoregulate

retain TMAO and urea to stay slightly hyper osmotic to seawater

Are marine teleosts hypo- or hyperosmotic to seawater?

Hyposmotic (must drink seawater)

how do freshwater fish osmoregulate

dont drink, produce dilute urine, β-chloride cells in gills to absorb salts

what are the three main types of jaw suspension in fish

amphistyly

autostyly/holostyly

hyostyly (sharks and bony fish)

what are pharyngeal teeth used for

grinding food

how is intestine length related to diet

carnivores - short intestine

herbivores - long intestine

what is hermaphroditism

having both male and female reproductive organs