Lecture 17 Animal Classification Phylum Arthropods Arthropods are

Lecture 17: Animal Classification Phylum: Arthropods ﺷﻌﺒﺔ ﻣﻔﺼﻠﻴﺔ ﺍﻷﺮﺟﻞ Arthropods are segmented coelomates ﺟﻮﻓﻴﺎﺕ with exoskeletons and jointed appendages ﺯﻭﺍﺋﺪ ﻣﻔﺼﻠﻴﺔ This phylum is represented in nearly all habitats in the biosphere. Arthropods are regarded as the most successful animal phylum. The diversity ﺍﻟﺘﻨﻮﻉ and success ﻭﺍﻟﻨﺠﺘﺢ of arthropods is largely due to three features: - body segmentation ﺗﻌﻘﻞ ﺍﻟﺠﺴﻢ , - a hard exoskeleton ﺟﻠﻴﺪ ﺧﺎﺭﺟﻲ ﺻﻠﺐ , - and jointed appendages ﺯﻭﺍﺋﺪ ﻣﻔﺼﻠﻴﺔ.

Phylum: Arthropods The body of an arthropod is completely covered by the cuticle, an exoskeleton constructed from layers of protein and chitin. The exoskeleton of arthropods is strong and relatively impermeable ﻏﻴﺮ ﻣﻨﻔﺬ to water. Arthropods have well-developed sense organs, including eyes for vision, olfactory receptors for smell, and antennae for touch and smell. Arthropods have an open circulatory system in which hemolymph fluid is propelled by a heart through short arteries into sinuses (the hemocoel) surrounding tissues and organs. Arthropods have evolved ﻣﺘﻄﻮﺭ a variety of specialized organs for gas exchange.

Phylum: Arthropods • They have claw ﻣﺨﻠﺐ like feeding appendages, chelicera ﺗآﺸﻴﺮ , ﺗآﺸﻴﺮ crustaceans ﺍﻟﺤﻴﻮﺍﻧﺎﺕ ﺍﻟﻘﺸﺮﻳﺔ have jaw like mandibles ﻓﻜﻮﻙ. • Have sensory antennae ﻗﺮﻭﻥ ﺍﺳﺘﺸﻌﺎﺭ and usually a pair of compound eyes ﺃﻌﻴﻦ ﻣﺮﻛﺒﺔ in addition to simple eyes. • Arthropods have been grouped into the phylum Arthropoda.

1 -Class Arachnida ﻃﺎﺋﻔﺔ ﺍﻟﻌﻨﻜﺒﻴﺎﺕ These include scorpions ﺍﻟﻌﻘﺎﺭﺏ , spiders ﺍﻟﻌﻨﺎﻛﺐ , ticks ﺍﻟﻘﺮﺍﺩ , and mites ﺍﻟﺤﻠﻢ. Nearly all ticks are blood-sucking ﻣﺎﺹ ﻟﻠﺪﻣﺎﺀ parasites on the body surfaces of most animals. In most spiders, respiration ﺍﻟﺘﻨﻔﺲ is carried out by book lungs ﺍﻟﺮﺋﺔ ﺍﻟﻜﺘﺎﺑﻴﺔ.

2 -class Insecta ﻃﺎﺋﻔﺔ ﺍﻟﺤﺸﺮﺍﺕ They live in almost every terrestrial habitat and in fresh water, and flying insects fill the air. The study of insect, (Entomology) is a vast field with many subspecialties, including physiology, ecology, and taxonomy…. etc. Class Insecta is divided into about 26 orders. • Many insects have one or two pairs of wings that emerge from the dorsal side of the thorax.

The Insects 750, 000 + species insects described, but may be 30 million species undescribed. Many adaptations make insects one of the most successful terrestrial animals. Exoskeleton for water conservation Tracheal System for gas exchange Metamorphosis ﺗﻐﻴﺮ ﺍﻟﻤﻈﻬﺮ Many types of mouth parts Flight

Specialized Mouthparts Modified mouthparts have allowed insects to diversify and take advantage of many different food sources. Modify generic structures for various food sources. Generalized Insect Mouthparts

The internal anatomy of an insect includes several complex organ systems. In the complete digestive system, there are regionally specialized organs with discrete functions ﻭﻇﺎﺋﻒ ﻣﻤﻴﺰﺓ. Metabolic wastes are removed from the hemolymph ﺍﻟﺪﻡ by Malpighian tubules ﺃﻨﺎﺑﻴﺐ ﻣﻠﺒﻴﺠﻲ , out pockets ﺟﻴﻮﺏ ﺧﺎﺭﺝ of the digestive tract. Respiration is accomplished by a branched, chitin-lined tracheal system ﺍﻟﺠﻬﺎﺯ ﺍﻟﻘﺼﺒﻲ that carries O 2 from the spiracles ﺍﻟﻔﺘﺤﺎﺕ ﺍﻟﺘﻨﻔﺴﻴﺔ directly to the cells. The insect nervous system consists of a pair of ventral nerve cords ﺣﺒﻠﻴﻦ ﻋﺼﺒﻴﻴﻦ ﺑﻄﻨﻴﻴﻦ with several segmental ganglia.

3 Kinds of Insect Metamorphosis Ametabolous Metamorphosis – only difference between larvae and adult are size; both are wingless. Silverfish ﺣﺸﺮﺓ ﺍﻟﺴﻤﻚ ﺍﻟﻔﻀﻲ , Order Thysanura ﻫﺪﺑﻴﺎﺕ ﺍﻟﺬﻳﻞ. After Flight… Hemimetabolous Metamorphosis – develop from egg to adult has several stages (instars) with smaller versions of adults called nymphs. Immature nymphs ﺍﻟﺤﻮﺭﻳﺎﺕ ﺍﻟﻐﻴﺮ ﻧﺎﺿﺠﺔ have no wings or genitalia until adult.

Incomplete or Hemimetabolous Metamorphosis

Holometabolous Metamorphosis – after hatching from egg, immatures are called larvae (very different body form than adult). After several instars, the last larval molt forms a pupa – undergoes radical body form change. Protective case may enclose pupal stage ﻃﻮﺭ ﺍﻟﻌﺬﺭﺍﺀ : Moths ﺍﻟﻔﺮﺍﺷﺔ use silk to make a cocoon ﺍﻟﺸﺮﻧﻘﺔ. Butterflies use the larval exoskeleton to make a chrysalis ﺍﻟﺸﺮﻧﻘﺔ. Adult emerges from case very different in body form – eclosion ﺍﻟﺘﻔﺮﻳﺦ.

Complete or Holometabolous Metamorphosis

You Decide?