Lecture 15: Animal Classification Sponges الأسفنج Kingdom: Animalia الحيوانات المتقدمة A)- Subkingdom: Parazoaنظائر البعديات Phylum: Poriferaالمساميات (الإسفنجيات) example: Sponges

1- Phylum: Porifera المساميات (الإسفنجيات) (Spongesالإسفنج ) Sponges are sessile جالسة with porous bodies أجسام مساميةand choanocytes The germ layers الطبقات المنبتةof sponges are not really tissues because the cells are relatively unspecializedغير متخصصة . Sponges lack nerves or muscles. Most sponges are marine بحرية and some live in fresh waterالماء العذب . The body of a sponge consists of two cell layers separated by a gelatinous region, the mesohyl. Most sponges are hermaphroditesخنثي , with each individual producing both sperm and eggs.

The body of a simple sponge resembles a sacيشبه كيس perforated with holesفتحات . Nearly all sponges are suspension feedersيتغذى على العوالق , collecting food particles from water.

Water Currents for Everything! Choanocytes use their flagella to create water currents through external pores called – ostia (sing. ostium,); incurrent pores. Bring food (bacteria, protists, etc.) and oxygen and remove metabolic wastes from the center of the sponge – spongocoel. Choanocytes use collar-like rings to filter food. Wastes and water flow out a central osculum (plural, oscula); an excurrent pore.

Sponges (Porifera)

Diploblastica الحيوانات ثنائية الطبقات Kingdom: Animalia الحيوانات المتقدمة B)- Subkingdom: Metazoaالبعديات Phylum: Coelentrataالجوفمعويات Class : Hydrozoaالهدريات example: Hydra الهيدرا & Obelia الأوبليا

This basic body plan has two Parts: the sessile polypالقرص الجالس and the floating medusaالميدوزا العائمة . The polyps adhere to the substratum by the aboral end and extend their tentacles, waiting for prey. Medusas (also called jellies) are flattened, mouth-downالفم لأسفل . They are carnivoresلاحم that use tentaclesالملامس arranged in a ring around the mouth to capture prey and push the food into the gastrovascular chamber for digestion. Muscles and nerves exist in their simplest forms.

1- Hydra They have a relatively simple body construction. The basic body plan is a sac with a central digestive compartment, the gastrovascular cavity التجويف الوائي-معوي. Hydra exist only in the polyp form. When environmental conditions are favorable, a hydra reproduces asexually by buddingالتبرعم

Triploblasticaثلاثية الطبقات Kingdom: Animalia الحيوانات المتقدمة Subkingdom: Metazoaالبعديات Phylum: Platyhelminthes المفلطحات 1- Class : Trematodaالتريماتودا example: Schistosoma البلهارسيا 2- Class: Cestoideaالسيستودا example: Taenia (Tapeworms) الدودة الشريطية

Platyhelminthes: Flatwormsالديدان المفلطحة They are acoelomatesعديمة التجويف السيلومي with gastrovascular cavities ولها تجويف وعائي-معوي They are living in marine, freshwater, and damp terrestrial habitatsوالبيئة الأرضية الرطبة . They also include many parasitic species, such as the flukesديدان البلهارسيا and tapewormsالديدان الشريطية . Flatworms are triploblasticثلاثية الطبقات , with a middle embryonic tissue layer, mesodermالطبقة الوسطى , which contributes to more complex organs and organs systems and to true muscle tissue.

Schistosoma البلهارسيا Trematodes parasitizeتتطفل على a wide range of hosts, and have complex life cycles with alternation of sexual and asexual stages. Many require an intermediate hostعائل وسيط in which the larvae develop before infecting the final hosts (usually a vertebrate) where the adult worm lives. The fluke Schistosoma infects 200 million people.