Shark vs. Dolphin Evolution
Sharks came from early fish and merely developed and speciated, whereas dolphins changed drastically between species and even habitats, until re-entering the water and evolving into their modern form
Similarities and Differences
Dolphins V. Sharks - Analogous and Homologous Structures
Analogous Structures
- Typically grey, white, or black
- Have large dorsal fins
- Backbone
- Vary in size, though typically large
- Possess complicated brains
- Carnivorous
- Live almost entirely in saltwater
- Typically solitary
- Have two dorsal fins
- Are cartilaginous fish, need oxygen from water, through gills
- Cold-blooded
- Have tails with vertical fins, move them sideways to move forwards
- Have a top speed in the 30s of mph
- Have a lateral line system to detect motion and vibrations
- Hunt and act in groups
- Have only one dorsal fin
- Are mammals, require air through lungs and have bones
- Are warm blooded
- Have tails with horizontal fins, move them up and down to go forwards
- Have a top speed in the 20s of mph
- Use echolocation and enlarged brain to detect movement from far away or under sand
Analogous Structures are similar pieces of anatomy in different organisms which signify commonality in function; Exist in Sharks and Dolphins in:
An Exploration into the Differences and Similarities of Two Aquatic Powerhouses
Homologous Structures
- Fins - dorsal, pectoral, etc
- "torpedo" shape
- grey coloration
- predatory behavior
Dolphins and Sharks relatively close, both marine vertebrates, have similar structures
Shark Evolution
Dolphin Evolution
Sharks are members of the class Chondrichthyes, cartilaginous fish - sharks, skates and rays
- they evolved from ancestral fishes, their earliest branching off from dolphin evolution
- more advanced and new than previous invertebrates, but some of the oldest organisms of vertebrates
Dolphins are members of class mammalia, intelligent and hairy organisms - whales, humans, dogs
- They evolved from early tetrapods, reptiles, then mammals, belonging to land
- These tetrapods slowly began to live closer to and utilize oceans more often, evolving to live in the oceans, eventually becoming dolphins
Homologous structures represent commonality in evolution; exist in Dolphins and sharks as:
- General skeleton
- Nervous system, eyes, brain, mouth, sharp teeth, jaws, cells
Vary significantly from analogous structures