Lecture 17 Animal Classification Phylum Arthropods Arthropods are

Lecture 17: Animal Classification Phylum: Arthropods �Arthropods are segmented coelomates with exoskeletons and jointed appendages �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 ﺟﻠﻴﺞ 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 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 a variety of specialized organs for gas exchange.

Phylum: Arthropods • They have clawlike feeding appendages, chelicerae crustaceans have jawlike 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 �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. � Metabolic wastes are removed from the hemolymph ﺍﻟﺪﻡ by Malpighian tubules ﺃﻨﺎﺑﻴﺐ ﻣﻠﺒﻴﺠﻲ , outpockets of the digestive tract. � Respiration is accomplished by a branched, chitin-lined tracheal system ﺍﻟﺠﻬﺎﺯ ﺍﻟﻘﺼﺒﻲ that carries O 2 from the spiracles 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, Order Thysanura. After Flight… �Hemimetabolous Metamorphosis – develop from egg to adult has several stages (instars) with smaller versions of adults called nymphs. Immature nymphs 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: � Moths use silk to make a cocoon. � Butterflies use the larval exoskeleton to make a chrysalis. �Adult emerges from case very different in body form – eclosion.

Complete or Holometabolous Metamorphosis

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