This document provides information about bony fishes, including: - Bony fishes make up about half of all vertebrate species, with over 25,000 species classified. They show great diversity and are classified mainly at the order or family level. - Characteristics of bony fishes include the presence of a swim bladder or lungs, bones, bony scales, and fin rays. - Ray-finned fishes are the most numerous and diverse group, with fins attached by fin rays. They are divided into subclasses with cartilaginous or bony skeletons and different tail and scale structures.

1. Chapt 10 Bony Fishes
Ichthyology
“the study of fish”

2. 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 is concentrated on order or family
rather than phylum (b/c phylum is too broad)
– Taxonomy of fishes are still changing as new
technology and research reveal new characteristics

3. Phylum Chordata
• Characteristics
– Presence of swim bladder or lung
– Bones
– Bony scales
– Fin rays

4. Coelacanths “primitive fish”
• Historic fish that give rise to modern day amphibians
• Were thought to be extinct 65 million years ago until
living specimens were discovered in 1938 and as
time goes on finding more and more individuals
“living fossils”
• Live at depths 150-250 meters
• Bony skeleton but vertebrae is almost all cartilage
(like sharks)
• Maintain high amount of urea to maintain
homeostasis
• Reproduction: ovoviviparous

5. Ray-finned Fishes
• Most numerous and diverse of ALL
vertebrates in ocean
• Characteristic-fins attached to body by fin ray

6. 2 major groups
• Subclass Chondrostei • Subclass Neopterygii
– Heterocercal tail – Homocercal tails
– Skeleton made mostly of • Backbone does not
cartilage extend into tail
– Ganoid scales – Cycloid OR Ctenoid
• Armored appearance scales
• Florida Gar • Both are thinner and
more flexible than ganoid
scales

7. 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

8. 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

10. Cardiovascular
• Close circulatory system: Heart, veins,
arteries
– Most complex we’ve seen so far!
– 4 chambered heart
• Draw diagram in your notes

12. 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

13. 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: Eyes Lack eyelids
• Most set on sides of face: each eye see own
independent view.

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Reproduction
• Vast: depends on species
– Blue headed wrasse can change sex
• Perch: separate sexes
– Males and females spawn eggs
• FEMALES MUCH LARGER THAN MALES DURING
BREEDING-> FULL OF EGGS (female on bottom ↑)
– Early spring in sandy, shallow sediments
– Females lay more than 20,000 eggs at a time;
male comes afterward to fertilize
• No parental care for young

15. Perch Anatomy