Shark Biology Study Notes
Table of Contents
- Introduction
- Anatomy & Physiology
- Sensory Systems
- Reproduction
- Ecological Roles
- Surprising Facts
- Interdisciplinary Connections
- Mind Map
- Technology Connections
- References
Introduction
Sharks are cartilaginous fishes belonging to the class Chondrichthyes. With over 500 species, sharks inhabit diverse marine environments from shallow coastal waters to the deep sea. Their evolutionary history spans over 400 million years, making them one of the oldest surviving vertebrate lineages.
Anatomy & Physiology
Skeleton
- Composed of cartilage rather than bone, providing flexibility and buoyancy.
- No ribs; internal organs are supported by strong abdominal muscles.
Body Shape
- Streamlined for efficient swimming.
- Heterocercal tail (asymmetric caudal fin) provides lift.
Skin
- Covered in dermal denticles (placoid scales) that reduce drag and protect against parasites.
- Denticles are structurally similar to teeth.
Internal Organs
- Large liver filled with oil for buoyancy.
- Spiral valve in the intestine increases nutrient absorption.
Diagram: Shark Anatomy
Sensory Systems
Vision
- Eyes adapted for low-light conditions.
- Some species possess a tapetum lucidum for enhanced night vision.
Olfaction
- Acute sense of smell; can detect blood at concentrations as low as one part per million.
- Nostrils (nares) are solely for smelling, not breathing.
Electroreception
- Ampullae of Lorenzini detect electrical fields produced by prey.
- Useful for hunting in murky waters or at night.
Lateral Line System
- Detects water movement and vibrations.
Hearing
- Inner ear detects low-frequency sounds, aiding in prey detection.
Reproduction
Modes
- Oviparous: Lays eggs in protective cases (“mermaid’s purses”).
- Viviparous: Gives birth to live young; some species have placental connections.
- Ovoviviparous: Eggs hatch inside the mother, and young are born live.
Mating
- Internal fertilization via claspers (modified pelvic fins).
- Some species exhibit parthenogenesis (asexual reproduction).
Development
- Gestation periods range from a few months to over two years.
- Low reproductive rates make populations vulnerable to decline.
Ecological Roles
- Apex predators: Regulate populations of other marine species.
- Scavengers: Clean up dead and decaying matter.
- Influence trophic cascades and maintain ecosystem balance.
Surprising Facts
- Some sharks glow in the dark. Deep-sea species like the lanternshark exhibit bioluminescence, using light-producing organs for camouflage and communication.
- Sharks can heal rapidly. Their skin contains compounds that promote fast wound healing and resist infections.
- Sharks sleep with their eyes open. Many species do not have eyelids and must keep swimming to breathe, so they rest one part of their brain at a time.
Interdisciplinary Connections
- Marine Biology: Understanding shark physiology and behavior.
- Genetics: Research on shark immune systems and regenerative abilities.
- Physics: Hydrodynamics of shark movement and skin structure.
- Chemistry: Study of bioluminescent compounds.
- Engineering: Biomimicry in design (e.g., drag-reducing surfaces).
- Medicine: Investigation of shark-derived compounds for wound healing and cancer resistance.
- Environmental Science: Impact of sharks on marine ecosystems and conservation strategies.
Mind Map
Technology Connections
- Underwater Robotics: Shark-inspired designs improve maneuverability and efficiency in aquatic drones.
- Medical Devices: Shark skin patterns inspire antimicrobial surfaces for hospitals.
- Sensors: Electroreception research informs development of sensitive underwater detectors.
- Artificial Intelligence: Modeling shark hunting strategies enhances autonomous navigation systems.
- Bioluminescence Applications: Study of shark and other marine bioluminescence leads to advances in imaging and biosensors.
References
- Recent Study: “Bioluminescence in sharks: Evolutionary trends and ecological implications” (Phys.org, 2021). Link
- “Sharks: Biology and Conservation” (Springer, 2022).
- “The role of sharks in marine ecosystems” (Marine Ecology Progress Series, 2020).
Additional Note
Bioluminescent organisms, including some sharks, contribute to the phenomenon of glowing waves at night, enhancing oceanic biodiversity and offering unique opportunities for interdisciplinary research and technological innovation.