Aquatic Biology: Fishes and Reptiles

Chondrichthyes (Cartilaginous Fishes)

• Internal Line System: A series of sensory receptors along the sides of the body detect water pressure, movement, and vibrations; aiding navigation, hunting, and predator avoidance.
• Buoyancy: Lack a swim bladder; rely on a large, oily liver for neutral buoyancy and active swimming to maintain position.
• External Anatomy: Cartilaginous skeleton, placoid scales (tiny, tooth-like scales), multiple gill slits, mouth on underside with teeth, nostrils, and well-developed eyes.

Osteichthyes (Bony Fishes)

• External Anatomy: Bony skeleton, operculum (bony flap covering gills), swim bladder (gas-filled sac for buoyancy control), scales, various fins for swimming, steering, and balance (dorsal, caudal, pectoral, pelvic).
• Swim Bladder: A gas-filled sac allowing bony fishes to regulate buoyancy.

Reptiles

• Oviparity (Egg-Laying): Female reptiles lay fertilized eggs, often in nests or buried in soil.
• Viviparity (Live Birth): Female reptiles give birth to live young, with nourishment provided through a placental-like structure or yolk sac.
• Ovoviviparity (Egg-hatching Inside the Mother): Female reptiles retain fertilized eggs inside their bodies until hatching.
• Orders of Reptiles: Testudines (turtles and tortoises), Squamata (lizards and snakes), Crocodilia (crocodiles, alligators), Sphenodontia (Tuataras).
• Internal Anatomy: Digestive system (mouth, esophagus, stomach, intestines, cloaca), respiratory system (lungs), circulatory system, excretory system, nervous system, reproductive system.
• Parthenogenesis in Reptiles: A rare form of asexual reproduction, observed in some lizards and snakes. Unfertilized egg develops into an offspring.

Amphibians

• Three Main Orders: Anura (frogs and toads), Caudata (salamanders and newts), Gymnophiona (caecilians).

Birds (Class Aves)

• Respiratory System: Lungs and air sacs; unidirectional airflow for efficient oxygen intake.
• Circulatory System: Four-chambered heart, maximizing oxygen delivery.
• Digestive System: Beak, crop, gizzard, and intestines.
• Nervous System: Relatively large brain, well-developed senses.

Mammals

• General Characteristics: Hair or fur, mammary glands, endothermy, four-chambered heart.
• Ways of Giving Birth: Placental mammals, marsupials, monotremes.
• Groups: Rodentia (rats, mice, squirrels), Chiroptera (bats), Carnivora (dogs, cats, bears), Primates (humans, monkeys), Artiodactyla (cows, deer), Perissodactyla (horses, zebras), Cetacea (whales, dolphins), Sirenia (manatees).

Aquatic and Marine Mammals

• Respiratory System: Adaptations to breathe air in water (e.g., complex social structures; echolocation). Examples include whales, dolphins, porpoises, seals, sea lions, walruses.

Explore the fascinating world of Chondrichthyes and Osteichthyes, alongside the reproductive strategies of reptiles. This quiz covers their anatomy, buoyancy mechanisms, and differences between these fascinating classes of animals. Test your knowledge of marine and reptilian biology.