Transcript lecture_17_taxonomy

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 ‫ التنوع‬and success ‫ والنجتح‬of 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
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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
‫ استشعار‬and usually a pair of
compound eyes ‫أعين مركبة‬in
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 ‫ التنفس‬is
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
‫رأس‬
‫صدر‬
‫بطن‬
‫قرون استشعار‬
‫عين مركبة‬
‫‪Fig. 33.33‬‬
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 ‫ الدم‬by
Malpighian tubules ‫أنابيب ملبيجي‬, outpockets of the digestive tract.
 Respiration is accomplished by a branched, chitin-lined
tracheal system ‫ الجهاز القصبي‬that carries O2 from the spiracles
directly to the cells.
 The insect nervous system consists of a pair of ventral nerve
cords ‫ حبلين عصبيين بطنيين‬with 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:
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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
You Decide?