Lecture 14 - Amphibians / Gnathostomata Flashcards
1
Q
What are the classes and subclass of Superclass: Gnathostomata
A
- Class: Chondrichthyes (cartilagenous fish)
- Class: Osteichthyes (bony fish)
-Subclass: Actinopterygii (ray-finned fish)
2
Q
What are the divisions of Superclass: Gnathostomata
A
- Sub-division: Teleostei (modern bony fish)
- Infradivision: Enteleostei (higher teleosts)
3
Q
What are the order and super order Superclass: Gnathostomata
A
- Superorder: Acantopterygii (spiny-rayed fish)
- Order: Perciformes
4
Q
What are the subclasses of Class: Chondrichthyes
A
- Subclass: Elasmobranchi
- Superorder: Batoidea (skates and rays)
- Superorder: Selachii (sharks)
5
Q
Explain Class: Chondrichthyes
A
- Skeleton of cartilage
- Placoid scales; teeth modified placoids
- Fusiform (spindle shaped) body
-Sense organs well developed
- Some predators; some filter feeders
Examples: Carcharadon carcharias (great white), C. taurus (ragged-tooth)
6
Q
Explain Superclass: Gnathostomata
A
- Skeleton bony
- Skin with mucous glands and embedded scales
- Four types of scales – cycloid (smooth edged), ctenoid (rough edged), lanceolate (sharp, long margins) and rhomboid (non-overlapping)
- Fins both paired and median
- Mouth terminal
- Respiration by gills
- Swim bladder often present
- Two-chambered heart
- Ten pairs of cranial nerves
7
Q
Explain Class: Osteichthyes
A
- Ray-finned fish
- Internal bony skeleton
- Scales of bone
- Gills covered by operculum
- Swim bladder present
- Feeding habits diverse: facultative filter feeders (sardine/pilchard)- pump water into their mouth
- Other filter feeders swim with their mouth open
- Opportunist feeders (trout and hake )- has different food sources. They are also often described as generalist predators
- Predators (yellowtail, snoek)
8
Q
Explain sea horses
A
- Males bear the offspring
- Female produces eggs, deposits it into male brood pouch
- He releases sperm to fertilize the eggs
- 2 to 4 weeks and he will give birth to hundreds of baby seahorses
- They receive no parental care
9
Q
Explain Class Amphibia
A
- Normally tetrapods
- Adult normally have lungs
- Metamorphosis
- Mostly moist, smooth skins
- Heart – 3-chambers; closed circulation
- External water source for fertilization generally
- Ectothermic
10
Q
Explain Evolution of amphibians from lobe finned fishes
A
- Lobe finned fish of Devonian are ancestral to amphibians
- Lobe finned fish- consist of 6 species of lungfish & 1specie of coelacanth.
- Lobe finned fish have fleshy fins and live in stagnant ponds or ponds that dry up. (in Africa, South America and Australia)
- They have lungs –breathe air
11
Q
Explain Two hypotheses describe evolution of amphibians from lobe‑finned fishes
A
- Lobe‑finned fishes that could move from pond‑to‑pond had an advantage over those that could not.
- The supply of food on land and the absence of predators promoted adaptation to land.
- Lobe finned fish diversified during carboniferous
12
Q
Class: Amphibia eggs and metamorphosis
A
- Generally, amphibian eggs are protected by a coat of jelly but not by a shell. They are not amniotic egg
- The young hatch into aquatic larvae with gills (tadpoles).
- The aquatic larvae usually undergo metamorphosis to develop into a terrestrial adult.
13
Q
Explain tetrapods
A
- All animals studied from this point on are tetrapods (have four limbs).
- Land animals use limbs to support their body since the air is less buoyant than water.
- About 4,200 species of amphibians belong to class Amphibia.
- The first amphibians diversified during the Carboniferous Period which is known as the Age of the Amphibians.
14
Q
What are the subclasses of Class: Amphibia
A
- Urodela
- Apoda
- Anura
15
Q
Explain Subclass : Apoda
A
- Apoda means without legs
- Legless, often sightless
- Worm-shaped body form (earthworm like)
- Caecilians are legless; most burrow in soil and feed on worms, etc.
- Reproduction involves a return to the water; “amphibian” refers to this need to return to water from land.
- They shed eggs into the water for external fertilization.
