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Fish Ho Suet Ying 6S (8).

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Presentation on theme: "Fish Ho Suet Ying 6S (8)."— Presentation transcript:

1 Fish Ho Suet Ying 6S (8)

2 General features any gill-bearing aquatic vertebrate (or craniate) animal which lacks limbs with digits most fish are ectothermic (Tuna, swordfish, and some species of shark are homoiothermic) has a streamlined body has gills or an accessory breathing organ has two sets of paired fins has skin that is usually covered with scales Fishes are divided into two main classes: chondrichthyes(fishes with cartilaginous skeletons) and osteichthyes(bony fishes)

3 Fish Chondrichthyes Osteichthyes Elasmobranchii Sarcopterygii
Holocephali Actinopterygii

4 Chondrichthyes (Cartilaginous fishes)
jawed fish with paired fins paired nares scales two-chambered hearts skeletons made of cartilage rather than bone large, oily liver for buoyancy swim bladder and lungs are absent forward swimming only 2 subclasses -Elasmobranchii (includes sharks , rays and skates) -Holocephali.

5 (A) Skeleton cartilaginous (cartilage is often partly calcified )
notochord lack ribs do not have bone marrow (red blood cells -> spleen , epigonal organ , Leydig’s organ

6 (B) Scales (placoid scales or dermal denticles)
covered with dermal teeth toothlike ( feel like sandpaper) protection in most cases streamlining (C) Respiration breathe through 5-7 gills (D)Excretion excrete urea as nitrogen waste (they are ureotelic, like adult amphibians and mammals). Tuna gills

7 (E) Reproduction (Three types)
OVIPAROUS like fish-- external fertilization of egg OVOVIVIPAROUS -embryos develop inside eggs - no placental connection VIVIPAROUS - oppose to laying eggs

8 Bullhead and its egg Catfish and its egg


10 Osteichthyes (Bony fish)
head and pectoral girdles are covered with large dermal bone eyeball is supported by a sclerotic ring of four small bones a lung or swim bladder Gas-filled swim bladder for buoyancy no fin spines (has lepidotrichia) an operculum bones are much heavier and less flexible than cartilage both forward and backward swimming 2 subclasses -Sarcopterygii -Actinopterygii

11 (A) Scales ( 2 types ) 1 . Ganoid scales
covered by enamel like substance called ganoin found in primitive bony fishes such as gars diamond-shaped thick non-overlapping

12 2 . Leptoid scales found on higher-order bony fish overlap in a head-to-tail direction 2 sub-groups - Cycloid scales Ctenoid scales *scaleless fish -sacrifice protection of scales presumably for added flexibility

13 (A) Sarcopterygii (fleshy-finned fish)
2 subclasses : Sarcopterygii & Actinopterygii (A) Sarcopterygii (fleshy-finned fish) a clade (traditionally a class or subclass) of fleshy-finned or lobe-finned vertebrates. only eight living species lobed paired fins, joined to the body by a single bone two dorsal fins with separate bases. 3 subclasses - Coelacanthimorpha — Coelacanths - Dipnoi — Lungfishes - Tetrapodomorpha — Tetrapods and their extinct relatives

14 A specimen of Latimeria Chalumnae
Queensland Lungfishes

15 (B) Actinopterygii ( ray-finned fish )
possess lepidotrichia or "fin rays" Considered more “advanced” than (A)Sarcopterygii – increased caudal symmetry - trend toward homocercal tail – fin membranes with fewer rays – reduction in dermal armor – loosening of maxillary and premaxillary bones, leading to a rounded mouth 2 subclasses - Chondrostei - Neopterygii

16 Gar Fish (Neopterygii) Nile Bichir (Chondrostei)

17 Excretion Reproduction
excrete nitrogen as ammonia, NH3, (they are ammoniotelic) Reproduction generally is external gametes are released in the water, where they can fecundate their counterpart and form the zygote.

18 Osteichthyes VS Chondrichthyes
Chondrychthyes Osteichthyes

19 Sources

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