4. The earliest known cartilaginous
fishes were ancient sharks that were
descended from bony-skeleton
placoderms. These primitive sharks
are older than the dinosaurs.
5. They swam in the world’s oceans
420 million years ago, 200 million
years before the first dinosaurs
appeared on land.
6. Cartilagenous fishes characterized by:
• paired nostrils
• skeleton completely cartilagenous with
no endoskeletal bone
• no swim bladder
• gill arches internal to gills
7. • Possess movable jaws
that usually have teeth
• Mouth is ventral,
underneath the head
9. Skates & Rays
• Flattened bodies
• Dermersal – live on the bottom
• Gill slits on the ventral side (bottom)
• Pectoral fins are flat and expanded
• Head fuses with pectoral fins with
eyes on top
10. Ratfish / Chimaeras
• Gill slits covered by a
flap of skin
• Mostly deep-water
fish
• Eat crustaceans and
mollusks
11. Most cartilaginous fishes live in
marine habitats all their lives,
but a few species of sharks and
rays live in freshwater during all
or part of their lives.
12. sharks:
bottom of coastal waters,
open sea
-needs: smaller sea animals to
hunt
rays:
bottom of saltwater or
freshwater
-needs: crustaceas, mullusks,
warmwater
13. Skates and rays
* warm temperature seas
Sharks
* cold deep
* the ocean floor
* move towards the coast for
feeding
14. There are just under 1000 living
species, all of which have
cartilaginous skeletons, even
though they are descended from
ancestors that had bone.
16. Megalodon
approximately 18m long (and with a mass
estimated at 50-100 metrics tones) it resembled
a massive great white shark and was the top
ocean predator of its era.
17. * Manta Ray
(about 30 feet
long)
* Basking Shark
(about 40 feet
long and 19 tons).
18. paired fins and flexible bodies
making movement in water very
feasible.
24. Body Plan: Chondrichthyes have bodies made
of cartilage instead of bone. They also lack ribs.
This allows for extreme flexibility. Their bodies
are covered in a thick skin. This skin is covered
dermal teeth, often called denticles, making it
feel like sand paper.
25. • Coelomate: Chondrichthyes have a coelomate.
• Segmentation:
Body segmentation is present, allowing for
specialization of body parts
• Symmetry: Chondrichthyes have bilateral symmetry
28. Digestive System
• Very short esophogus
• Stomach can be up to 1/3 the length of the
shark
• Intestine is really small, only about a foot
29. Respiratory System
• Must swim to force water through their gills
• Some such as nurse sharks can get enough
oxygen so they do not need to swim
30. Circulatory System
Heart is Built upon the pattern similar to other fishes.
The Heart is consists of a sinus venosus, artrium, ventricle and
conus with three rows of valves.
32. • Ampullae of Lorenzini
• Jelly filled canals that can detect electrical
fields, magnetic fields, temperature,
salinity, water pressure, etc.
33. TYPE OF NERVOUS SYSTEM:
* Chondrichthyans have myelin sheaths around the
axons of their neurons.
* This permits much more rapid transmission of nerve
impulses.
* They also have a single, hollow, ectodermal, dorsal
nerve cord with a large anterior end ( which is the
brain).
34. * They have three main sections to their brains,
one which in controls ability to smell, another
which is responsible for vision, learning, and
motor responses, and the last which coordinates
movement, muscle tone, and balance.
35. Reproductive System:
Chondrichthyans reproduce by internal
fertilization
This is in order to protect young from highly
hypertonic environment, since they do not have
the ability to survive in the salty water until
later
36. Mating
One clasper will rotate 90º and will be inserted into
the female’s cloaca
Clasper will expand cartilaginous spurs to anchor in
the female
