Transcript Nerve activates contraction

Principals of General Zoology (Zoo-103)
Zoology Department, 1431-1432H
1
KINGDOM: ANIMALIA
DIVISION:
INVERTEBRATES
)‫(ليس لها عمود ِفقَري‬
‫الالفقريات‬
Phylum:
Mollusca ‫شعبة الرخويات‬
• Mollusca includes snails ‫ القواقع المائية‬and slugs ‫القواقع األرضية‬, octopuses ‫ األخطبوط‬and
squids ‫الحبار‬.
• Most mollusks are marine, though some inhabit fresh water, and some snails
and slugs live on land.
• Mollusks are soft-bodied animals, but most are protected by a hard shell ‫صدفة‬
‫ قوية‬of calcium carbonate.
• All mollusks have a muscular foot for locomotion, a visceral mass ‫جزء حشوي‬
with most of the internal organs, and a mantle ‫البرنس‬.
• Most mollusks have separate sexes, with gonads located in the visceral
mass, and some are hermaphrodites.
1- Class:
Gastropoda ‫البطنقدميات‬
e.g. snails ‫القوقع الحلزوني‬
• Most Gastropoda are marine, but there are also many freshwater
species.
• The anus and mantle
cavity are above
the head in adults.
1- Class:
Gastropoda
• Most gastropods are protected by a spiraled shell ‫صدفة حلزونية‬.
• Other species have lost
their shells entirely and
may have chemical
defenses against predators.
• Many gastropods have distinct
heads with eyes at the tips of
tentacles ‫المالمس الرأسية‬.
• They move by their foot.
• Some species are predators.
2- Class:
Cephalopoda
e.g. Octopus
‫الرأسقدميات‬
‫األخطبوط‬
•Cephalopods use rapid movements toward their prey which they capture with several
long tentacles.
•A mantle covers the visceral mass, but the shell is reduced and internal in squids ‫الحبار‬,
missing in many octopuses.
•
The foot of a cephalopod
(“head foot”) has been
modified into the
muscular siphon and
parts of the tentacles
•
Most octopuses live on
the seafloor.
•
Cephalopods have an
active, predaceous ‫مفترسات‬
lifestyle.
•
They have a welldeveloped nervous system
with a complex brain and
well-developed sense
organs.
B)- Phylum: Annelida ‫الحلقيات‬
Class: Oligochaeta ‫قليالت األشواك‬
e.g. earthworm ‫دودة األرض‬
• All annelids (“little rings”) have segmented bodies.
• Annelids live in the sea, most freshwater habitats,
and damp soil.
• The coelom of the earthworm, a typical annelid, is
partitioned by septa ‫مقسم بفواصل‬, but the digestive tract,
longitudinal blood vessels, and nerve cords penetrate
the septa and run the animal’s length.
• Most annelids, including earthworms, burrow in sand
and silt.
e.g. earthworm
• The digestive system consists of a pharynx ‫مريء‬, an
esophagus ‫بلعوم‬, crop ‫حوصلة‬, gizzard ‫قانصة‬, and intestine ‫أمعاء‬.
• The closed circulatory system carries blood with oxygencarrying hemoglobin through dorsal and ventral vessels
connected by segmental vessels.
• In each segment is a pair of excretory tubes, metanephridia,
‫ كلية بدائية‬that remove wastes from the blood and coelomic fluid.
• Earthworms are cross-fertilizing hermaphrodites.
• Some earthworms can also reproduce asexually by
fragmentation ‫ بالتقطيع‬followed by regeneration.
Earthworm
Phylum Nematoda: )‫شعبة النيماتودا (الديدان الخيطية‬
Roundworms are pseudocoelomates covered by tough cuticles ‫جليد قوي‬
e.g. Ascaris
• Roundworms are found in most
aquatic habitats, wet soil, moist
tissues of plants, and the body fluids
and tissues of animals.
• Some species parasitize animals
‫تتطفل‬
‫على الحيوان‬.
• They range in length from less than 1
mm to more than a meter.
• The body of Nematode is covered
with a tough exoskeleton, the cuticle.
• They have a complete digestive tract
‫قناة هضمية كاملة‬.
• Nematodes usually engage in sexual
reproduction ‫التكاثر الجنسي‬