Chapter 20
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What does the name osteichthyes refer to?
Bony fish
Compare bone versus cartilage including advantages and disadvantages.
Bone -stronger : better protection and structural support *advantage -less flexible (stiff) *disadvantage -heavier : more energy expenditure for movement and floatation *disadvantage -better blood supply : heals faster *advantage Cartilage -flexible and lightweight *advantage -doesn’t heal fast *disadvantage -no protection or structural support *disadvantage
What are the three groups of fishes included within Osteichthyes?
Ray-finned fishes (Actinopterygii), lobe-finned fishes (coelacanths, lungfishes)
What is the main difference between the coelacanths plus lungfishes and the ray-finned fishes?
Lobe-finned fishes (coelacanths & lungfishes) have a lobe with bones that are homologous with tetrapods while ray-finned fishes do not have a lobe or the homologous bones.
What are homologous structures?
Similar trait or characteristics from a common ancestor
What are fin rays?
A bony element that supports fin membranes
How do fin rays relate to the taxonomic name Actinopterygii?
Fin rays relate to the name Actinopterygii because the fins in these animals are supported by fin rays (spines or soft rays or both)
List the two types of fin rays, their characteristics and function
SPINES Characteristic -unsegmented, unbranched, hard Function -protection & structural support SOFT RAYS Characteristic -segmented, branched, flexible Function -maneuverability
What are the two main functions of scales?
Protection, hydrodynamics (easier to swim)
What evolutionary trend is evident regarding the number and size of the scales in many groups of bony fishes?
Decrease in number and size of the scales during evolution. Large, heavy, bony plates -> small, lightweight scales -> no scales
List and define the 4 main body shapes found in bony fishes.
Anguilliform, compressiform, fusiform, and globiform (globular).
Fusiform
Torpedo shaped body, efficient for swimming (e.g. tuna & billfishes
Anguilliform
Eel shape body, energy efficient, not fast, fit in tight places (e.g. eels)
Compressiform
Compressed body shape laterally or dorso-ventrally flattened, hard to see, fit into small places (e.g. many coral reef fishes & flatfishes)
Globiform
Global shaped body (e.g. porcupinefish)
List and define the 5 main coloration patterns found in bony fishes
Cryptic, disruptive, advertisement, ocelli and countershading.
Cryptic
Blending in with the environment (camouflage)
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Sexual selection (flashy colors to show off male sex) bight colors in males show they are healthy and have the best genes for survival
Disruptive
Break the outline of body so predators cannot tell what they are (striped fish-> dark light shows only the light color of the stripes, light light shows only the dark color of the stripes -> confuses predator)
Ocelli
False eye spots (a spot on fish that looks like an eye to trick predators that the head is located there)
Countershading
Pelagic fishes (dark while looking down on the fish, light while looking up at the fish = camouflage)
What is the lateral line system?
-Sensory system that detects vibrations in water. -It is a series of canals with pores and neuromasts (cupola & cilia). -Signal to brain depends on the direction of bending of the cilia.
What are neuromasts?
-A sensory organ in the lateral line system. -It is made of cupola and cilia that moves with water movement that enters the canal of the lateral line through the lateral line pore.
What are the main functions of the lateral line system?
To detect vibration in the water -schooling (pack of fishes moving together) -from predators -from prey -from obstacles