Diversity in living organisms

Diversity in living organisms

17)                Echinodermata includes spiny skinned organisms with calcareous skeleton. They are triploblastic, coelomate, marine and free-living. Water vascular system is an important feature. Starfish and Holothuria are examples of this phylum.

18)                All chordates have a notochord, dorsal nerve cord and paired pharyngeal gill slits/pouches. Also they are triploblastic, coelomic and bilaterally symmetrical.

19)                Vertebrates and Protochordates are grouped under Chordata. 

20)                The Protochordates possess notochord at some or the other stage of their life. E.g. Balanoglossus, Amphioxus.

21)                Vertebrates show true vertebral column and endoskeleton. Complex body organization and differentiation is seen.

22)                The five classes of vertebrates are Pisces, Amphibia, Reptilia, Aves and Mammalia.

	Pisces	Amphibia	Reptilia	Aves	Mammalia
Habitat	Aquatic	Both land and water	Some terrestrial, others aquatic	Terrestrial (aerial)	Usually terrestrial, few aquatic.
Skin	Covered with scales/plates	Smooth skin with mucus glands and lacking scales	Waterproof skin with scales	Mostly covered with feathers	Covered with hair and contains sweat and oil glands.
Control of body temperature	Coldblooded	Coldblooded	Coldblooded	Warm- blooded	Warm- blooded
No. of heart chambers	2	3	3(except crocodiles)	4	4
Respiration	Gills	Gills, lungs or skin	Lungs	Lungs	Lungs
Mode of reproduction	Oviparous	Oviparous	Oviparous	Oviparous	Viviparous
Locomotion	Tail and fins	Limbs	Limbs	Wings	Limbs
Examples	Rohu, shark, sea-horse, sting ray	Frog, salamander, toad	Crocodile, snake, turtle, lizard	Pigeon, ostrich, hen, duck	Human, whale, bat, lion

23)                The endoskeleton in fish may be cartilaginous or bony.

24)                Mammary glands produce milk in mammals to nourish the young ones.

25)                Binomial nomenclature, developed by Carolus Linnaeus, uses two names to identify an organism. The first name is the generic name beginning with a capital letter whereas the second name is the species name which begins with a small letter.

26)                Binomial nomenclature makes it possible to identify every species of organisms in the astounding diversity of life present in our planet. 

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