Chapter 20 Flashcards
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
Gonochorism
Only one sex, either female or male NOT both.
Sequential hermaphroditism vs simultaneous hermaphroditism
Hermaphroditism-> both sexes
Sequential-> change sex during life
Simultaneous-> male and female at the same time *DO NOT FERTILIZE YOURSELF!
Protandry
Male -> female (e.g. clownfish)
*good for monogamous(one partner) relationships -> bigger female fish to produce mor eggs
*when elder female dies oldest male turns into a female
Protogyny
Female -> male (e.g. parrot fishes)
*good for polygamous(more than one partner) -> one male mates w/ multiple females
*fishes that were able to survive long enough to become a male = better genes for survival -> pass on genes as male
*male sneakers (adult males that look like juveniles) -> evolved to look like juveniles so they can mate with females without competing with the big male adults b/c they think they are juveniles
Sexual dimorphism
Two shapes or forms
*external characteristics -> define if male or female
Broadcast spawning
Male squirts sperm into water, female either relates their eggs or keep them
Describe why the discovery of the first coelacanth was so important
It was thought that coelacanth were extinct for 65 million years ago with the dinosaurs.
When and where was the first coelacanth discovered?
In 1938 Marjorie Courtenay-Latimer found one in South Africa
What is the genus name of this animal in honor of?
The genus name Latimeria chalumnae is in honor of the women who found it, Marjorie Courtenay-Latimer
How many living species of coelacanths have been described so far?
Two living species have been described so far
What do we mean when we say that coelacanths are “living fossils”?
It means that the species is still alive today
What are the closest living relatives to the tetrapods?
Lungfishes
What does the word “tetrapod” refer to?
Four legs
Name the 3 groups of tetrapods.
Amphibians, Reptiles, and Mammals
Where are lungfishes found today?
Africa, South American, and Australia
What is unique about the anatomy of lungfishes?
That they have lungs and gills, meaning they can breathe in and out of the water
