Prepared by : Nada H. Lubbad Phylum Arthropods Prepared by : Nada H. Lubbad

General characteristic: Arthropod , Greek word comes from – Arthros = “ Joint” , podos = “ foot” . Bilateral symmetry; metameric body, consisting of head, thorax, and abdomen; or cephalothorax and abdomen Jointed appendages; primitively, one pair to each somite; appendages often modified for specialized functions. Exoskeleton of cuticle containing protein, lipid, chitin, and often calcium carbonate secreted by underlying epidermis and shed (molted) at intervals. Complex muscular system, with exoskeleton for attachment, striated muscles for rapid actions, smooth muscles for visceral organs; no cilia. Reduced coelom in adult; most of body cavity consisting of hemocoel (sinuses, or spaces, in the tissues) filled with blood. Complete digestive system; mouthparts modified from appendages and adapted for different methods of feeding.

Open circulatory system, with dorsal contractile heart, arteries, and blood sinuses. 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. 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. 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. 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 Uniramia Crustacea Class Arachnida : spiders ticks scorpions Class Insecta: insects Class Chilopoda : centipedes Class Diplopoda: millipedes Class Malacostraca crabs lobsters shrimp

Subphylum Chelicerata كلابيات القرون Body divided into 2 regions: Abdomen. Prosoma / Cephalothorax (fused head & thorax). Lack jaws. Have 6 appendages & no antennae. First appendages form chelicerae (frequently fangs) are modified for tearing food apart. Class Arachnida : spiders Ticks القرّاد Scorpions عقرب

Spider External Anatomy

Spiders have six spinnerets المغازلthat can produce up to seven different types of silk. Spider silk is made of protein and is one of the strongest natural substances in the world. Silk is produced in liquid form, but dries upon contact with air. All spiders produce silk, but not all spiders spin webs. Silk is also used for shelter, reproduction, and drag lines for jumping. Respiration in spiders by means of pair of book lungs.

Scorpion Tick

Subphylum Uniramia أحادية الشعبة Insects (Class Insecta) over 75% of all animal species. first animals to develop flight Largest group of arthropods. 3 pairs of legs. 3 main body part sections. 2 pairs of eyes. Most insects have wings, however in many species these are vestigial. Have advanced excretory system composed of malpighian tubules. Exchange gasses through a complex tracheal system. Insects usually have specialized jaws/mouthparts suited to their ecological niche.

Metamorphosis 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. Two types: Incomplete metamorphosis: Larva similar to adult, with differing body proportions. 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. They have five pairs of legs. They live near or on the ocean floor. Live on land and water. They have antennae. breathe by gills. one pair of large claws. 4 pairs of walking legs.

Crustacean Shrimp

Lobster

Crab