Fish 🐟 Flashcards
What are the two main groups of fish, and which species are included in each?
- Bony fish = most fish
- Cartilaginous = sharks, rays, chimaera, sawfish
How would you describe the general shape of fish, and what is the benefit of it?
They have a fusiform shape, which is very streamlined & efficient for moving through water quickly.
What does it mean when a fish is ectothermic?
They are cold-blooded, and must create their own body heat or obtain it from their environment.
Which fish species are NOT ectothermic?
Tuna + some sharks
What are the muscles of fish composed of, and how does this effect their movement?
Myomeres = blocks of skeletal muscle, separated by connective tissue.
They move in an S-shape as each side alternates contractions, allowing forward motion.
What is the purpose of fins on a fish?
propulsion & stabilization
Which fins are responsible for propulsion through water?
- Caudal tail fin (thrust + direction)
Which fins are responsible for stabilization when swimming through water?
- Pectoral fins (control yaw + pitch, braking with drag)
- Pelvic fins (control pitch)
- Dorsal fin (control roll)
- Anal fins (control roll)
What is important to know about the vertebrae of fish?
They have a lot; exact number varies based on age/size. Also, they articulate with their ribs.
What is a gas bladder, aka swim bladder? And where is it located in the anatomy of a fish?
Gas bladder = internal gas-filled organ in bony fish, responsible for buoyancy.
Located ventral to spinal column + dorsal to stomach, in dorsal portion of the body cavity.
What are the differences between a fish with a physostomous swim bladder, vs. a fish with a physoclistous swim bladder?
Physostomous = has a connection between their swim bladder + digestive tract, can gulp air to inflate the swim bladder.
Physoclistous = no connection for swim bladder, extracts gas from blood to inflate swim bladder.
Why can a marine fish’s gas bladder take up less body volume (5%) than a freshwater fish’s (7%)?
Because marine fish live in highly salinated/salty water, so water is more dense, allowing them to float better.
What are the 5 types of scales seen in fish? Which one is the most common?
- placoid = very hard, do not grow
- cosmoid = grow as fish grows
- ganoid = articulating joints
- ctenoid = spiny border = most common!
- cycloid = smooth border
What is the function of the mucus that envelopes all fish?
It acts as a protective barrier, with fungicidal and bactericidal properties. Protects from pathogens + environmental stressors.
Which physical structures are responsible for a fish’s sense of smell?
The olfactory bulbs connected to their cerebrum.
Which physical structures are responsible for a fish’s sense of vision?
Their optic lobes.
What is important to know about a fish’s sense of hearing?
It is not well developed.
Fish have a structure called the _______ that is located along both sides of its body. It is composed of many sense receptors that can detect vibrations & currents in the water.
Lateral line
What is the function of a fish’s gills?
They allow a fish to breathe underwater by extracting oxygen (O2) from water (H2O)
Can you name all of the parts in a fish’s gills? Including the protective structures.
- gill slits
- gill arches
- filaments
- lamellae
- gill rakers
- opercula
What is the importance of gill filaments and their lamellae?
They are the primary site for gas exchange, facilitating the uptake of oxygen from water. The lamellae provide a large surface area, rich with capillaries to maximize efficiency.
Which protective structures are seen on the outside and inside of a fish’s gills? And what are their function?
Outside has the opercula, which acts as a protective covering to keep things from hitting the gills.
Inside has the gill rakers, which act like a sieve or filter to keep things out of the gills.
What is important to know about the blood flow within a fish?
It only flows through the heart once, in a single circulation.
What is the generalized pathway for blood flow in a fish? (major structures, nonspecific)
Heart > gills > body > heart.
