Module 10 - Fish Flashcards
What are the three main groups of fish?
- Jawless fish (Class Agnatha);
2. Cartilaginous fish (Class Chondrichthyes); 3. Bony fish (Class Osteichthyes);
What determines how fast a fish can swim?
The speed of a fish is about 10 body lengths per second. Locomotion is made with myomeres (Muscles composed of zigzag band). The barracuda can swim 43km/h.
Explain the ecological role of fish.
Fish remove problematic insect nymphs and other organism (mosquito). They provide food for higher predators and live in symbiotic relationships with other animals (e. g. Hippo & Tilapia).
What is the largest freshwater fish in SA?
Sharp-tooth catfish, 59 kg.
What is a fish?
All fish are vertebrates, aquatic, ectothermic (‘cold blooded’), breath by means of gills, move by means of fins and generally covered in scales.
Describe scales
- Cover skin of body of bony fish (growth rings)
- Protection from injury, predators and parasites
- Can slide over one another and distort while swimming
- Hydrodynamic
Explain a fish’s senses
- Sight:
- Eyes are round (less distortion)
- No eye-lids
- Poor 3D vision (no overlap in FOV from eyes)
- Most see in color - Taste: barbels with specialized cells
- Hearing: Lateral line detects sound and pressure waves, amplified by swim bladder
- Pheromones: used in breeding season and as alarm signal
- Touch: barbels
Explain Fish feeding behaviour
- Carnivores
- Herbivores
- Filter-feeders
- Scavengers
- Parasitic feeders
Breeding types in fish
- Oviparous: Egg (external fertilisation) - Larva - Juvenile - Adult
- Ovoviviparous: internal fertilisation: Egg develops internaly
Breeding strategy in fish
Varies from no parental care to elaborate nests and defensive behavior
What determines a fish’s growth?
- Temperature
- Age
- Size of water body
- Food availability
Explain coloration in fish
- Bright colors warn of predators
- Translucent larvae and young
- Dull or cryptic coloration to blend in
- Countershading (Camouflage and temperature regulation)
