Question

Marine animals with streamlined body and having cartilaginous endoskeleton belongs to which class of the superclass Pisces ?

• A. Osteichthyes
• B. Cephalaspidomorphi
• C. Myxini
• D. Chondrichthyes

Answer 1

Answer:

D. Chondrichthyes

Super class Pisces:

Class – Chondrichthyes:

• They are marine animals with streamlined body and have cartilaginous endoskeleton. 
• Mouth is located ventrally. 
• Notochord is persistent throughout life.
• The skin is tough, containing minute placoid scales.
• Teeth are modified placoid scales which are backwardly directed. 
• Their jaws are very powerful. These animals are predaceous. 
• Due to the absence of air bladder to swim constantly to avoid sinking 
• Heart is two-chambered ( one auricle and one ventricle).
• Some of them have electric organs (e.g., Torpedo) and some possess poison sting (e.g., Trygon). 
• They are cold blooded (poikilothermous) animals, i.e., they lack the capacity to regulate their body temperature.
• Sexes are separate.
• In males pelvic fins bear internal fertilisation and many of them are viviparous.

Examples:

• Scoliodon (Dog fish)
• Pristis (Saw fish)
• Carcharodon (Great white shark)
• Trygon (Sting ray)