Handout

Cartilaginous Fish
Handout

Characteristics:

1. The skeleton of the cartilaginous fish is out of a flexible bone- cartilage. The skeleton does not have any bone.
2.These fish have dorsal fins, an anal fin, a pair of ventral fins and a single caudal fin.
3.The swim bladder and lungs are absent and the liver is filled with oil to provide buoyancy to the body while swimming.
4.The heart consists of two chambers like other fish and amphibians.
5.The cartilaginous fish habitat comprises mostly of creeks and rocks where they can get their prey easily. Sharks are mostly found near the seabed.
6.These fish have jaws which have tiny teeth, with the upper row of teeth having a layer of enamel and the lower row of teeth is made up of bone tissue, which attaches them to the skin. The teeth are modified and are replaced by new teeth, when the older ones become worn out.
7.Sharks and stingrays have an opening, called spiracle or gill slits that is situated on both sides of the head right behind the eyes, for breathing.
8.The pectoral fins of the shark are called claspers and used for copulation. There are three ways in which sharks reproduce; oviparous, where the female lays eggs which takes a few months to develop, ovoviviparous, where the eggs are hatched in the oviduct and the embryo develops in the uterus and viviparous, in which the gestation period of the embryo is about one year.
9.The sharks feed on other sea animals like zoo plankton, other smaller fish, whales and shellfish, etc.

Food:
Cartilaginous fish live in the sea. They are most common in warm seas. There habitat varies from the different type. Some live in the depths of the seas, and some near the surface. Some live in coastal waters, and some far out at sea. Most of the cartilaginous fish are carnivores. What they eat ranges from small worms and mussels to large fast swimming fish and marine animals. The sharks also eat their own kind. There are fewer than 100 attacks on humans a year from cartilaginous fish

Name:
Class Chondrichthyes means the jawed, cartilaginous fish with a flexible skeleton made of cartilage.
Representative Organism:

SHARKS
Best known species :
• great white shark, tiger shark, and the hammerhead are apex predators, at the top of the underwater food chain.

Famous for:
• extraordinary skills as
• predators fascinate and frighten humans
• even as their survival is under serious threat from fishing and other human activities.

CHIMAERA
They live in temperate ocean floors below approximately 2,600 metres depth, with few occurring at depths shallower than 200 metres
• known informally as ghost sharks, ratfish
• They may be the "oldest and most enigmatic groups of fishes alive todayAt one time a "diverse and abundant" group their closest living relatives are sharks, though in evolutionary terms they branched off from sharks nearly 400 million years ago and have remained isolated ever since, typically confined to deep water
• They lack sharks' many sharp and replaceable teeth, having instead just three pairs of large permanent grinding tooth plates


Vocabulary:

Enamel-the hard white outer layer of teeth

Spiracle- an opening that is situated on both sides of the head right behind the eyes, for breathing.

claspers- The pectoral fins of the shark used for copulation.

gill- one of the organs behind the head of a fish that allows it to breathe

medulla oblongata- the lowest part of your brain that is connected to your spinal cord and controls the way that your heart and lungs work

olfactory- relating to your sense of smell

Fun Facts about Sharks

When a shark's tooth falls out they grow a new one. They have an endless number of teeth. A shark will grow its tooth back if the tooth is broken or falls out. A shark could go through a thousand teeth in its life time

A shark's jaw is loaded with teeth.

Sharks can have from five to seven gills. The six gilled shark contains the substance called "tape turn". This is the same substance that makes a cat’s eye green. The six gilled shark needs this substance to see in dark, deep water.

A dolphin will attack a shark to protect its young.

Dolphins usually kill sharks.

If you rub against a shark, you may bleed because their skin is like sharp teeth.

Work Cited

Alphonse, Marlene. "Cartilaginous Fish." Buzzle Web Portal: Intelligent Life on the Web. Web. 21 Feb. 2011. .

"Sharks." Michael Poliza Photography. Web. 21 Feb. 2011. .

"Cartilaginous Fish." Borglumbio. Web. 21 Feb. 2011. .

"Ancient Noncoding Elements Conserved in the Human Genome." Science. Web. 21 Feb. 2011. .

"* Cartilaginous Fish - (Biology): Definition." * Home. Web. 21 Feb. 2011. .

"Fishes - A Slippery Subject." ReefQuest Centre for Shark Research Home. Web. 21 Feb. 2011. .

Diversity within groups

Subclass Elasmobranchii, containing
Superorder Batoidea the rays and skates
Superorder Selachimorpha the sharks
Subclass Holocephali, containing
Order Chimaeriformes the Chimaeras

Representative Organisms

SHARKS


Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Selachimorpha



Best known species :
• great white shark, tiger shark, and the hammerhead are apex predators, at the top of the underwater food chain.

Famous for:

• extraordinary skills as
• predators fascinate and frighten humans
• even as their survival is under serious threat from fishing and other human activities.


CHIMAERA
(http://en.wikipedia.org/wiki/Chimaera)


Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Holocephali
Order: Chimaeriformes

• They live in temperate ocean floors below approximately 2,600 metres (8,500 ft) depth, with few occurring at depths shallower than 200 metres (660 ft).
• known informally as ghost sharks, ratfish
• They may be the "oldest and most enigmatic groups of fishes alive today."[2] At one time a "diverse and abundant" group (based on the fossil record), their closest living relatives are sharks, though in evolutionary terms they branched off from sharks nearly 400 million years ago and have remained isolated ever since, typically confined to deep water.[2] (interesting)
• They lack sharks' many sharp and replaceable teeth, having instead just three pairs of large permanent grinding tooth plates

Nervous System

The nervous system of a shark is much simpler than that of a human's. Sharks have a spinal chord and a medulla oblongata, which is responsible for controling balance. They also have olfactory bulbs for smell as well as optic lobes for sight and a cerebellum responsible for the movement of the fish.

Habitat and food source

Cartilaginous fish live in the sea. They are most common and likely to appear in warm seas. Their habitat varies from the different types. Some live in the depths of the seas, while others near the shores. Some live in coastal waters, other far out in the sea. Mostly cartilaginous fish are carnivores. What they eat ranges from small worms and mussels to large fast swimming fish such as marine animals. The sharks also do happen to eat other sharks. There are fewer than 100 attacks by cartilaginous fish on humans per year.

Reproducing and Life Cycle

The ways cartilaginous fish reproduce varies. Some of them lay eggs, others of them are born alive. Some give birth to 60 offspring. Mostly it is fewer. The male has two organs called claspers, which release sperm into the female, where the egg is fertilized. Once the fish are born their parents don't take care of them. Some even appear to eat their babies.

Unique Characteristics

1.The skeleton of the cartilaginous fish is out of a flexible bone- cartilage. The skeleton does not have any bone.
2.These fish have dorsal fins, an anal fin, a pair of ventral fins and a single caudal fin.
3.The swim bladder and lungs are absent and the liver is filled with oil to provide buoyancy to the body while swimming.

4.The heart consists of two chambers like other fish and amphibians.
5.The cartilaginous fish habitat comprises mostly of creeks and rocks where they can get their prey easily. Sharks are mostly found near the seabed.


6.These fish have jaws which have tiny teeth, with the upper row of teeth having a layer of enamel and the lower row of teeth is made up of bone tissue, which attaches them to the skin. The teeth are modified and are replaced by new teeth, when the older ones become worn out.

7.Sharks and stingrays have an opening, called spiracle or gill slits that is situated on both sides of the head right behind the eyes, for breathing.
8.The pectoral fins of the shark are called claspers and used for copulation. There are three ways in which sharks reproduce; oviparous, where the female lays eggs which takes a few months to develop, ovoviviparous, where the eggs are hatched in the oviduct and the embryo develops in the uterus and viviparous, in which the gestation period of the embryo is about one year.
9.The sharks feed on other sea animals like zoo plankton, other smaller fish, whales and shellfish, etc.
An interesting fact about sharks is that they have a huge mass and have to keep swimming continuously. If they stop swimming, they will sink like a stone.

10.Approximately 400 million years ago, the ancestors of the bony fish and cartilaginous fish seperated in the Silurian period. The bony fish belong to the class Osteichthytes and have a bone in their body, whereas cartilaginous fish are a family of Chondrichthyes, and have a skeleton made of cartilage. The bony fish have a pair of gills that are situated inside their bodies, and the cartilaginous fish have gill slits on the outer side of their bodies, present on both sides. In the cartilaginous fish, the teeth, nostrils on the side of the head and the tiny tooth like scale are not fused together to the jaw. Fertilization of the eggs occurs through the process of internal fertilization unlike bony fish, where fertilization takes place outside the body.

11.Sharks occupy a variety of ecological niches, and the different species pursue a diversity of prey; from minute plankton and small invertebrates right up to large marine mammals. Some of the smaller reef sharks such as the Epaulette shark have narrow flexible bodies and strong pectoral fins that allow them to hunt through small crevices in coral reefs in pursuit of ‘cryptic’ prey. Such species occupy an ecological niche similar to the Moray eel

12.They occupy a huge range of ecological niches, from the huge, planktivorous Basking and Whale sharks to the bottom dwelling Carpet sharks, and probably the ultimate pelagic predator; the Great White shark.

Evolutionary tree/ Cladogram

The amphibians and some of the non-vertebrate chordates like hagfish are most closely related as they have evolved close after the cartilaginous fish.
Cartilaginous fish first appeared during the Devonian period about 400 million years ago. Their kind expanded during the Carboniferous and Permian.

• How long ago did humans share a common ancestor with this group?

Cartilaginous fishes are the living group of jawed vertebrates that comes from the common ancestor of human and teleost fish 530 million years ago

Meaning of the name

Class Chondrichthyes means the jawed, cartilaginous fish with a flexible skeleton made of cartilage.