Lecture 15: Animal Classification

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

1- Phylum: Poriferaالمساميات (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)

Diploblasticaالحيواناتثنائية الطبقات Kingdom:Animaliaالحيواناتالمتقدمة B)- Subkingdom:Metazoaالبعديات Phylum:Coelentrataالجوفمعويات Class :Hydrozoaالهدريات example:Hydra الهيدرا & Obeliaالأوبليا

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:Animaliaالحيوانات المتقدمة Subkingdom:Metazoaالبعديات Phylum:Platyhelminthesالمفلطحات 1- Class :Trematodaالتريماتودا example:Schistosomaالبلهارسيا 2- Class:Cestoideaالسيستودا example: Taenia (Tapeworms) الدودة الشريطية

Platyhelminthes: Flatwormsالديدان المفلطحة • They are acoelomatesعديمة التجويف السيلومي with gastrovascular cavitiesولها 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.

Schistosomaالبلهارسيا • 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.

Lecture 15: Animal Classification