Close relatives of arthopods

CLOSE RELATIVES

         a. Insect (hexapoda)

         b. Arachnida (eight legs)

         c. Crustacean (more than eight legs)

         d. Chilopoda (100 legs)

         e.  Diplopoda (1000 legs)

Characteristics of above mentioned categories:-

A.    INSECTA

1.     THEY ARE TRACHAETED ARTHOPODA.

2.     BILATERAL SYMMETRY.

3.     PREANSENCE OF THREE GERMS LAYERS DURINGS EMBRYO DEVELOPMENT.

4.     BODY SEGMENT ARE DIVIDED INTO THREE DISTINCT REGION ie. HEAD,THOREX AND ABDOMEN. 

5.     EXOSKELTON IS HARD.

6.     THOREX CONSIST OF THREE SEGMENTS i.e PROTHOREX, MESOTHOREX, AND METATHOREX. HAVING ONE PAIR OF LEGS IN EACH SEGMENT HAVE A PAIR OF WINGS.

7.     ABDOMEN COMPRISES OF 7-11 SEGMENTS.

8.     ALIMENTARY CANAL TUBULER SATRT WHICH OPEN ANTERIORLY INTO MOUTH AND END INTO ANUS

9.     BLOOD IS DEVOID OF RED BLOOD CELLS AND YELLOWISH GREEN IN COLOUR.

10.            RESPIRATORY SYSTEM CONSIST OF TRACHEA WHICH OPEN EXTERIORLY BY MEANS OF PAIRED SPIRICALS

11.            CIRCULATORY SYSTEM IS OPEN TYPE.

12.            NERVOUS SYSTEM IS COMPOSED OF GANGLIONIC MASSES WHICH ARE INTER-CONNECTED WITH NERCVE CORD.

13.            EXCREATION TAKES PLACE BY MEANS OF MALPHAGIANS TUBULES.

14.            REPRODUCTION IS USUSLLY SEXUAL BY SOMETIMES BY MEANS OFM PARTHOGENESIS.

15.            SEXES ARE SEPRATES BUT SOMETIMES MALES AND FEMALE SEX ORGANS ARE PRESENT ON SAME INDIVIDULES e.g COTTANY CUSTION SCALE.

16.            METAMORPHOSIS IS THE COMMON PHENOMENA IN INSECT.

17.            SENCE ORGANS WHICH ARE USUALLY PRESENT IN THE INSECT INCLUDED ARE COMPOUND EYES, AUDIOTORY (ORGAN OF HEARING) ,ALFECTORY (ORGAN OF SMELL) ,GUSTATORY(ORAGN OF TASTE),CHROCLOTONAL (SOUND PRODUSING ORGAN AND LIGHT PRODUCING ORGAN)

B.     ARACHNIDA(EIGHT LEGS)

1.    THEY ARE AIR BREATHING ARTHOPODA.

2.    BODY DIVIDED INTO TWO REGIONS i.e CEPHOTHOREX AND ABDOMEN.

3.    FOUR PAIR OF LEGS.

4.     ANTENNAE ARE ABSENT eg. SCORPION, SPIDER, TICT.

C.      CRUSTACEAE(MORE THAN EIGHT LEGS)

1.    POSSESS TWO PAIRS OF ANTENNAE.

2.    FIVE PAIRS OF LEGS.

3.    USUALLY AQUATIC AND BREATHING THROUGH GILLS.

4.    EXOSKELTON LIMY, HARD AND CHITIN.

5.    HEAD AND THOREX REGION OFTEN FUSED INTO CEPHOTHOREX eg. CRAB, SHRIMP.

D.    CHILOPODA (100 LEGS)

1.    TERRESTIAL, ACTIVE ANIMALS.

2.    BODY DARSO VENTRALLY FLETON.

3.    ONE PAIR OF LEG ON EACH SEGMENT, LATERALS IN POSITION.

4.    ONE PAIR OF LONG ANTENNAE.

5.    POISION CLAWS ON THE FIRST BODY SEGMENT.eg. CENTIPEDE.

E.     DIPLOPODA (1000 LEGS)

1.    LIVE IN HUMID DARK PLACES UNDER STONES OR WITH THE ROTTING LOG AVOID LIGHT.

2.    TERRESTRIAL SLOW MOVING.

3.    BODY CYLIMDRICAL WITH SEGMENTATION CLEARLY VISIBLE.

4.     ONE PAIR OF SHORT ANTENNAE.eg. MILLIPEDA.

5.    TWO PAIR OF LEGS AND TWO PAIR OF SPIRACLES IN MOST SEGMENTS.