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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