Download Class Insecta

Phylum Arthropods
Prepared by : Nada H. Lubbad
 General characteristic:
o Arthropod , Greek word comes from – Arthros = “ Joint” , podos = “ foot” .
o Bilateral symmetry; metameric body, consisting of head, thorax, and abdomen; or
cephalothorax and abdomen
o Jointed appendages; primitively, one pair to each somite; appendages often modified for
specialized functions.
o Exoskeleton of cuticle containing protein, lipid, chitin, and often calcium carbonate secreted by
underlying epidermis and shed (molted) at intervals.
o Complex muscular system, with exoskeleton for attachment, striated muscles for rapid actions,
smooth muscles for visceral organs; no cilia.
o Reduced coelom in adult; most of body cavity consisting of hemocoel (sinuses, or spaces, in the
tissues) filled with blood.
o Complete digestive system; mouthparts modified from appendages and adapted for different
methods of feeding.
o Open circulatory system, with dorsal contractile heart, arteries, and blood sinuses.
o Respiration by :
• Body surface in larvae of some aquatic insects.
• Gills borne on thoracic or abdominal appendages in Crustacea
• Tracheae (air tubes), in Insecta.
• Lung books in Archnida.
• Tracheal lungs in some true spiders.
o Paired excretory glands called coxal, antennal, or maxillary glands present in some, homologous to
metameric nephridial system of annelids; some with other excretory organs, called malpighian
tubules.
o Nervous system of annelid plan, with dorsal brain connected by a ring around the gullet to a double
nerve chain of ventral ganglia; fusion of ganglia in some species; well developed sensory organs.
o Sexes usually separate, with paired reproductive organs and ducts; usually internal fertilization;
oviparous or ovoviviparous; often with metamorphosis; parthenogenesis in some.
Phylum Arthropoda
Subphylum
Trilobita
Subphylum
Chelicerata
Subphylum
Uniramia
Subphylum
Crustacea
Class Arachnida :
spiders
ticks
scorpions
Class Insecta:
insects
Class Chilopoda :
centipedes
Class Diplopoda:
millipedes
Class Malacostraca
crabs
lobsters
shrimp
 Subphylum Chelicerata
‫كالبيات القرون‬
o Body divided into 2 regions:
 Abdomen.
 Prosoma / Cephalothorax (fused head & thorax).
o Lack jaws.
o Have 6 appendages & no antennae.
 First appendages form chelicerae (frequently fangs) are modified for tearing
food apart.
 Class Arachnida :
 spiders
 Ticks ‫القراد‬
ّ
 Scorpions
‫عقرب‬
Spider External Anatomy
o Spiders have six spinnerets ‫ المغازل‬that can produce up to seven different types of silk.
o Spider silk is made of protein and is one of the strongest natural substances in the world.
o Silk is produced in liquid form, but dries upon contact with air.
o All spiders produce silk, but not all spiders spin webs.
o Silk is also used for shelter, reproduction, and drag lines for jumping.
o Respiration in spiders by means of pair of book lungs.
Scorpion
Tick
 Subphylum Uniramia ‫أحادية الشعبة‬
Insects (Class Insecta)
o over 75% of all animal species.
o first animals to develop flight
o Largest group of arthropods.
o 3 pairs of legs.
o 3 main body part sections.
o 2 pairs of eyes.
o Most insects have wings, however in many species these are vestigial.
o Have advanced excretory system composed of malpighian tubules.
o Exchange gasses through a complex tracheal system.
o Insects usually have specialized jaws/mouthparts suited to their ecological niche.
 Metamorphosis
o Most insects undergo a process of metamorphosis .
 major changes in the form or structure of some animals or insects that happens as the
animal or insect becomes an adult.
o Two types:
1. Incomplete metamorphosis:
o Larva similar to adult, with differing body proportions.
o Undergoes a series of molts resulting in adult phenotype.
2. Complete Metamorphosis:
 Larva is very unlike adult phenotype
 Envelopes self in a cocoon or chrysalis where body breaks-down and reforms into adult form.
Centipedes (Class Chilopoda)
a. one pair of legs per segment.
b. poisonous fangs for killing prey.
c. long antennae.
 Millipedes (Class Diplopoda)
a. two pairs of legs per segment.
b. one pair of short antennae.
c. usually harmless vegetarians.
 Subphylum Crustacea
The largest group of crustaceans is class Malacostraca ‫القشريات لينة الهيكل‬, which includes
lobsters, crabs, shrimps and others.
o They have five pairs of legs.
o They live near or on the ocean floor.
o Live on land and water.
o They have antennae.
o breathe by gills.
o one pair of large claws.
o 4 pairs of walking legs.
Crustacean Shrimp
Lobster
Crab