bio presentation chondrichthyes

TOPIC : CHONDRICHTHY

ES(CARCHARODO

N)Prepared by : Peviterjit Kaur

6BE

Introduction Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone.They are divided into two subclasses:Elasmobranchii (sharks, rays and skates)Holocephali (chimaera, sometimes called ghost sharks, which are sometimes separated into their own class).“Chondros” means cartilage, “ictis” means fish (both from the Greek) the name chondrichthyes is for fishes with cartilaginous endoskeleton.

Chondrichthyes

This is the picture of the Great White Shark,

Carcharodon carcharias

http://en.wikipedia.org/wiki/File:White_shark.jpg

IntroductionThe Scientific Classification

KINGDOM : Animalia

PHYLUM : Chordata

INFRAPHYLUM : Gnathostomata

CLASS : Chondrichthyes

Examples of Chondrichthyes

What are the morphological

characteristics of Chondrichthyes…?

Characteristics of Chondrichthyes


Some of their general characteristics include: Cartilaginous skeleton (derived characteristic)JawsRespiration through gillsInternal fertilizationMay lay eggs or give birthAcute senses, include lateral lines


Teeth

Sharks have a unique feeding adaptation, which involves replacing their teeth periodically. This is possible because their teeth are not attached to any skeletal element of the jaw. They replace their teeth by having them ride up on the inner side of the jaw, where they rotate into position as they reach its crest. The exact mechanism by which the teeth move is not fully understood. Shark teeth are so distinct that the form an important taxonomic characteristic.


Feeding

Larger sharks and rays are suspension feeders that feed on mostly plankton and small fish. The rest are carnivores.

Characteristics of

ChondrichthyesShark sense

Sharks have sharp vision, but they cannot distinguish between colors. They have such a keen sense of smell that their noses are often termed "living noses". Sharks also have batteries of receptors, which allow them to respond to mechanical forms of energy such as touch, vibration, water currents, sound, and hydrostatic pressure. Sharks also have a sensitive electrosensory system. This system allows them to detect electromagnetic fields. It is believed that this sense aids the animal in their final stages of prey capture.


Swimming and Body Form

Sharks have a streamlined body that reduces turbulence. Sharks have special paired pectoral and pelvic fins that provide them with lift in the water. The caudal fins propel them forward. The dorsal fin acts as a stabilizer. They do not have swim bladder, therefore if they were to stop moving they would most likely sink to the bottom of the ocean.


Evolutionary history:

Chondrichthyes had an origin about 400 million years ago and have a common ancestor to the bony fishes. The earliest sharks had terminal mouths and long upper jaws. During the Carboniferous, about 310 million years ago, a Chondrichthyes developed. In the late Paleozoic and during the Mesozoic.


Many sharks achieved new levels of organization that included:•Pectoral fin skeleton •Development of anal fin •New ventral element of the vertebral column

Then in the lower Jurassic of the Mesozoic, about 170 million years ago, they formed modern hyostylic jaw suspensions, a shortened upper jaw, and well-developed vertebrae.

What is the structure of the

sexual reproduction organ of the

Chondrichthyes…?

Sexual Reproduction

Organ Reproduction

Compared to other fish, sharks have a unique form of reproduction that is almost mammalian. They have internal fertilization. The male transfers the sperm into the reproductive tract of the female using its claspers on its pelvic fins. Depending on the species of shark, it can either be oviparous (the eggs hatch outside the mother’s body), ovoviviparous (the fertilized egg is retained in the oviduct), or viviparous (the young develops in the uterus and nourished by the mother prior to birth).

The Reproductive Organ of a Male

Shark

Oviparous Foetus...

Reproduction

Male Shark Reproductive

Organs

Female Shark Reproductive

Organ

What is the life cycle of

chondrichthyes…?

Life Cycle of Chondrichthyes

The great white shark gives birth to 2-14 baby sharks at a time. It has one litter every two years. The eggs are fertilized and hatch inside the mother. When born, they are called pups. Pups are 4-5 feet long at birth and weigh about 40 pounds. The pups swim away from the mother immediately after birth to hunt and care for themselves. There is no care given by the mother.

http://www.kidzone.ws/imageschanged/sharks/sharklifecycle.gif

Hope you enjoyed the presentation

&received some

input…Thank you…!!!

bio presentation chondrichthyes

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