Phylum Arthropoda

Phylum Arthropoda

Introduction  to the Animal kingdom

The living organism is divided into  two main kingdoms

            The Animal kingdom

The plant kingdom

The Animal kingdom,

                                    Is further divided into lower and higher animals

Which classified in to phyla  or sub-kingdom. Each phylum singular  includes a group of animals  which possess common characteristics .each phylum is further divided in many classes, each family in to many genera (singular, genus) and each genus into number of species .

            One of the most important phyla  is phylum chordate which includes all the  higher animals vertebrates ( animal with back bone)  comprising mammals, birds, reptiles, frog, and fishes .The other  eleven phyla includes lower animals or invertebrates (animals without a backbone)

Important groups (phyla) of animals

VERTEBRATES:

PHYLUM CHORDATA

Class Mammalia           e.g. Man, cat, horse, bat, whale,

Class Aves                   e.g. Birds, fowls,          

Class Reptilia                e.g.  turtles, snakes, lizards, alligators

Class Amphibia            e.g.   frogs, toads, salamanders,

Class Pisces                 e.g.   fishes

INVERTEBRATES:

Phylum  Protozoa                     e.g.  one celled animals (amoeba, euglena, paramecium)

Phylum porifiera                        e.g.   sponges.

Phylum coelenterata                  e.g.   jellyfish, corals, etc

Phylum echinodermata               e.g. .    starfish, sea, urchins 

 Phylum platyhelminthes            e.g. tapeworm, liver fluke

 Phylum nemathelminthes           e.g.  roundworm 

 Phylum annulata (annelida)       e.g.  earthworm, leeches. 

 Phylum mollusca                      e.g. snail, slug, oyster 

 Phylum bryozoa (polyzoa)        e.g.  moss animals, sea mates

 Phylum brachiapoda                e.g. lamp shells

 Phylum nemertinea                   e.g. nemertines

 Phylum trochelminthes e.g. rotifers, wheel animals cules

                                    .

 Phylum ctenophora                  e.g. sea walnuts, comb jellies

 Phylum Arthropoda           e.g. crabs, prawn, spiders, scorpions, centipedes, millipedes,

                                                     Peripatus   and insects                   

Main characters of phylum arthropoda

It is the  largest  phylum in animals kingdom and the animals belonging to it differ in structure , but have some common characters

SCLEROTISED EXOSKELETON: They possess a hard outer covering of the body  called  exoskeleton made up of substance called chitin

BILETERALLY SYMMETRICAL: The animals of phylum arthropoda  are bilaterally symmetrical  (the right and left sides of their body are similar in structure). They have mouth at anterior and anus at posterior  ends of body.

SEGMENT BODY: The body of these animals is made up of a series of rings or segments .These body segments are generally grouped in to two or three body regions

PAIRED JOINTED APPENDAGES : Some of the body segments possess outgrowths such as antennae, legs, and wings. The antennae, legs and wings are always in pairs.

BODY CAVITY: The body cavity is called  haemocoel  and it is filled with liquid substance is called haemolymph or blood.

ALIMENTARY CANAL OR GUT : The alimentary  canal or food tract is divided into  fore  gut, mid gut, and hind gut.

BLOOD VESSEL: The blood vessel is a narrow tube –like dorsal vessel which lies in the upper part of the body just above the alimentary canal. It consist of a posterior heart and an anterior aorta.

CENTRAL NERVOUS SYSTEM: The central nervous system lie inside just below the alimentary canal (except brain) at the  ventral (lower) side of the body.

MUSCLES OF BODY:  The muscles of body are almost entirely made up of striated fibers.

Main classes  of phylum arthropoda

      Different  classification of phylum arthropoda has been given by different authors. However, major and widely accepted main classes of arthropoda are as under;

CLASS ONYCHOPHORA: In these animals the body is almost cylindrical, apparently unsegmented and differentiated into head and trunk. The head contains a pair of short, thick ringed  antennae,  a pair of simple eyes, a pair of oral papillae and a circular mouth below. The trunk bears at least 15 pairs of  stumpy legs .the respiration takes place through tracheae. Examples  Peripatus.

CLASS CHILOPODA: In these animals the body is long flattened and divided into head and trunk. The head bears  a pair of long antennae and usually two clusters of simple eyes the trunk carries one hundred legs (a pair of legs on each segments), the first pair modified as poison-claws. They respire through tracheae .Examples centipedes (hundred legged worms)

CLASS DIPLOPODA: In these animals, the body is almost long, cylindrical and divided in to head and trunk. The head contain a pair of short antennae  and usually two clusters of simple eyes . The trunk contain one thousand legs, the first segments of trunk bears  no legs ,the second, third and fourth segments bear a single pair and other segments contain two pairs of legs. The respiration through tracheae. Examples Millipedes (thousand legged worms)