Question

External Features Internal Features Subphylum Trilobitomorpha Class Trilobita Subphylum Chelicerata Class Arachnidia Class Merostomata Subphylum Myriapoda Class Chilopoda Class Diplopoda Subphylum Crustacea Class Malacostraca Class Maxillopoda Subphylum Hexapoda Class Insecta Class Entognatha

Answer 1

Ans) Subphylum Trilobitomorpha Class Trilobita :

External features :

Trilobita existed around 380 million years in seas they belonged to arthropods but now has become extinct external feature of this subphylum is
1. presence of body skeleton externally
2. Body is segemented
3. They have jointed limbs.

Internal features :

Digestive system : food tube is simple , mouth is located at the the entry of anterioventral end.

They process open type of circulatory system.

Locomotion : One pair of biramous legs is present.

Reproduction : They are generally oviparous.

Subphylum Chelicerata :

External features :

1. Their body is segmented
2. They have jointed limbs
3. There body is covered with exoskeleton

Internal features:

1. They have presence of open circulatory system
2. Heart is tube like shaped

Class Arachnodia :

External features :

They belong to phylum Arthopods
Wings or antennae or absent
Mandible is present which helps in chewing and biting their prey.
Eight appendages are present
Cephalothorax due to fused thorax and head.

Internal features :

Tubular shaped stomach
It have presence of one or two gonads situated in abdomen
They usually lay eggs
They posess two type of eyes: lateral evolved from compund eyes and have tapetum that increases the ability for light collection
Medianocelli it develop from the transfer folds of ectoderm.

Class Merostomata :

External features :

Their Exoskeleton majorly consist of 3 parts
1. Prosoma: It has shape like horseshoe located in the front part
2. Opisthosoma: It is middle region
3. Telson: It is a thin tail
The prosoma region consist of couple of pair of simple and a pair of compound eyes.

Internal features :

Merostomata: Internal features
1. Carapace it has horseshoe shape and is thick
2. It posess caudal spine which is long
3. Respiratory structure is gill found behind the abdominal appendages sixth pair.

Subphylum Myriapoda :

External features :

They have head and trunk
Presence of a pair of antennae
A pair of simple eyes
Mandibles and maxillae are present.

Internal features :

In Myriapods, spiracle are present for breathing
Presence of tubular shaped heart which is generally long.

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