Class ChondrichthyesClass Chondrichthyes

Mirabel, Camille Joyce Mercado, Pia Alyssa Rivera, John David

E T Y M O L O G Y“Chondros’’ - Cartilages

“Ichthyos’’ - Fish

Class ChondrichthyesCharacteristics:Characteristics:

Cartilaginous fishes Streamlined form with heterocercal tail Cartilaginous skeleton Leathery skin With placoid scales ( dermal denticles ) Restricted notochord Mouth and two nostrils ventral Jaws and paired appendages Male claspers Eggs with large yolk

M O R P H O L O G Y

Taxonomical HierarchyTaxonomical Hierarchy Kingdom Animalia Phylum Chordata Subphylum Vertebrata Infraphylum Gnathostomata Class Chondrichthyes Subclass Elasmobranchii

Orders Cladoselachii, Pleuracanthodii ( extinct sharks )

Orders Squaliformes Order Rajiformes Subclass Holocephali

Subclass Elasmobranchii Sharks (Selachii) and the rays & skates

(Batoidea) lives in most oceans in the world

Circulatory SystemCirculatory System

Four chamber heart: sinus venosus, atrium, ventricle, and conus arteriosus.

One direction of flow: Heart Gills Body

Ectotherms/Endotherms

Reproductive System Reproductive System (Male)(Male) Both

testes functional

Seasonal reproduction cycle

Sperm stored in seminal vesicles

Both claspers functional

Reproductive System Reproductive System (Female)(Female) One functional ovary in most

viviparous species

Seasonal reproductive cycle

Fertilization in nidamental gland

Shark MatingShark 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

Subclass Elasmobranchii:Orders Cladoselachii, Pleuracanthodii

extinct sharks

Order Squaliformessharks, body spindle-shaped; 5-7 pairs of

lateral gills not covered by operculum, pectoral fins not enlarged example: Squalus

Order Rajiformesskates, rays and sawfishes, body

spreadout, pectoral fins enlarged and attached to head and body; five pairs of gill slits on ventral side, spiracles large

Subclass Holocephali

• chimaeras or ghost fish , gill slits covered with operculum;

• spirally closed; aberrant shaped; jaws with tooth plates;

• single nasal opening without scales; accessory clasping organs in male ;

• lateral line an open groove, Chimaera

Nervous SystemNervous SystemCerebellum is smallMedulla Oblongata is produced laterally

into restiform bodies

Digestive SystemDigestive SystemThe mouth in holocephali is small as

compared to the wide mouth of Elasmobranch

It is bounded by three lips-like fold and equipped with the tooth plate having irregular surface and sharp cutting Edges

Urogenital SystemUrogenital SystemThe kidney of holocephalians is

opisthonepric having a large number of uriniferous tubules and built upon the basic pattern other fishes.

Circulatory SystemCirculatory SystemHeart 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.

Respiratory SystemRespiratory SystemA Mandibular pseudobranch is absent and

hyoid bear only a Posterior Hemibranch.The first,second and the third branchial

arches have Holobranch but the forth Has a hemibranch.