Chapt 10 Bony Fishes Ichthyology “the study of fish”
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