Lecture 16: Animal Classification

1. Lecture 16: Animal Classification KINGDOM: ANIMALIA DIVISION: INVERTEBRATES اللافقريات (ليس لها عمود فِقَري)

2. Phylum: Molluscaشعبةالرخويات • Mollusca includes snailsالقواقع المائية and slugs القواقع الأرضية, octopuses الأخطبوط and squidsالحبار. • 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 shellصدفة قوية of calcium carbonate. • All mollusks have a muscular foot for locomotion, a visceral massجزء حشويwith most of the internal organs, and a mantleالبرنس. • Most mollusks have separate sexes, with gonads located in the visceral mass, and some are hermaphrodites.

3. 1- Class: Gastropodaالبطنقدميات e.g. snailsالقوقع الحلزوني • Most Gastropoda are marine, but there are also many freshwater species. • The anus and mantle cavity are above the head in adults.

4. Most gastropods are protected by a spiraled shellصدفة 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 tentaclesالملامس الرأسية. • They move by their foot. • Some species are predators.

5. 2- Class: Cephalopoda الرأسقدميات e.g. Octopus الأخطبوط • 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 well-developed nervous system with a complex brain and well-developed sense organs.

6. B)- Phylum: Annelida الحلقياتClass: Oligochaetaقليلات الأشواكe.g. earthworm دودة الأرض • 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.

7. 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 oxygen-carrying 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 بالتقطيع followed by regeneration.

8. Earthworm

9. 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