Chapt 10 Bony Fishes

Ichthyology “the study of fish”

Phylum Chordata

• Class Actinopterygii– “modern bony fish”– 25,000 species or ½ of all

vertebrate species– So diverse no one

characteristic can differentiate them from sharks, skates, and rays (cartilaginous fish)

– Taxonomy of fishes are still changing as new technology and research reveal new characteristics

Phylum Chrodata

• Characteristics– Presence of swim bladder or lung– Bones– Bony scales– Fin rays

2 major groups• Subclass Chondrostei

– Heterocercal tail– Skeleton made mostly of

cartilage– Ganoid scales

• Armored appearance• Florida Gar

• Subclass Neopterygii– Homocercal tails

• Backbone does not extend into tail

– Cycloid OR Ctenoid scales

• Both are thinner and more flexible than ganoid scales

Body Shapes-determined by habitat

• Fusiform- streamlined shape for active swimmers

• Laterally compressed- flattened so can maneuver though corals

• Flattened: bottom-dwellers

• snakelike: burrowing fish

Respiration and Circulation

Respiration

• Gills: receive oxygen and remove CO2, and maintain salt balance– Made of gill filaments: blood flows in opposite

direction of incoming H2O• Water must continuously pass over gills

– Meets with blood with lower O2 and higher CO2• Diffusion moves from where to where?????

– Fish actually “pump” H2O over gills

Cardiovascular

• Close circulatory system: Heart, veins, arteries– Most complex we’ve seen so far!– 4 chambered heart

• Draw diagram in your notes

• What does it mean to have an open circulatory system?

KOI Circulatory System :D

Swimming and Movement

Muscle Contractions

• W shaped bands of muscle• Movement occurs when

muscle contracts. – Alternate from one side to

the other – Starts at anterior and travels

to posterior end

• Contractions start at different areas in the body for different fish = different swimming patterns.

Staying neutrally bouyant

• Buoyancy– Swim bladder: gas filled sac; add and remove to

adjust buoyancy• SCUBA divers must adjust air in BCD for same purpose

– To go down: let air/gas out– To go up: add air/gas

Fish Coloration

5 important types you need to know

Important to fish survival

• Help the fish to – Find food– Communicate – Attract mates– Defend itself from

predators– Recognize species – Conceal themselves

• Pigments: found in cells called chromatophores

Different types

• 1. Structural colors– Produced by light reflecting

from crystals located on chromatophores

• 2. Obliterative Countershading – Found on fish living in

pelagic zone (open ocean) – Dark on the top and white

on the bottom– Why?

More types.. • 3. Disruptive Coloration

– Distract predator – Lines, stripes, fake eyes

• Trying to aim predator in the wrong direction

• Cryptic Coloration– Sneaky– Use colors to ambush prey

• Poster Colors– Bright, showy colors that

advertise territorial ownership or sexual displays

Nervous System & Reproduction

Nervous System• Brain, spinal cord, nerves• Senses

– Olfaction: sense of smell: olfactory pits (nostrils)– Taste: receptors on head, jaws, tongue, mouth

and barbels on some fish (catfish)– Hearing: internal ears – Sight: Eyes Lack eyelids

• Most set on sides of face: each eye see own independent view.

• Lateral Line: Detect movement in water

Reproduction• Vast: depends on species– Internal and external

sexual reproduction – Some care and protect

young, others do not

• Perch: separate sexes– Males and females

spawn eggs– Early spring in sandy,

shallow sediments– Females lay more than

20,000 eggs at a time; male comes afterward to fertilize

Perch Anatomy