Lecture 15: Kingdom: Animalia INVERTEBRATES اللافقريات (ليس لها عمود فِقَري)

4- Phylum: Nematoda (Round worm) Example: Ascaris sp. 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. 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

5- Phylum: Annelida (Segmented worms) Class: Oligochaeta قليلة الأشواك Example: Earthwormsديدان الأرض All annelids (“little rings”) have segmented bodies. Annelids live in the sea, most freshwater habitats, and wet soil. The coelom of the earthworm is partitioned by septa 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.

Earthworms: The digestive system consists of a pharynx بلعوم, an esophagus مرئ, 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 بدائية that 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.

Earthworm

6- Phylum: Mollusca Mollusca includes snailsالقواقع and slugs البزاقات, octopus الأخطبوط and squid الحبار. Most mollusks are marine, 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 قوية of calcium carbonate. All mollusks have a muscular foot for locomotion, and a mantle البُرنّس. Most mollusks have separate sexes, with gonads, and some are hermaphrodites.

1- Class: Gastropodaالبطنقدميات e.g. snails الحلزون (القوقع الأرضي) Most Gastropoda are marine, but there are also many freshwater species. The anus and mantle cavity are above the head in adults.

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. They move by their foot.

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. Most octopuses live on the seafloor قاع البحر. Cephalopods have an active, predator مفترسات. They have a well-developed nervous system with a complex brain and well-developed sense organs.