Bilaterally symmetrical (左右对称).PPTVIP

Kingdom animalia (動物界) Cnidarians/coelenterates (刺胞動物) Annelids (環節動物) Molluscs (軟體動物) Arthropods (節肢動物) Echinoderms (棘皮動物) Vertebrates (脊椎動物) (Fishes 魚類, Amphibians 兩棲動物, Reptiles 爬行動物, Birds 鳥, Mammals 哺乳動物) Cnidarians (刺胞動物) Example: Obelia(藪枝螅), coral (珊瑚), sea anemone (海葵), jellyfish(水母), and Hydra (水螅), Radially symmetry (輻射對稱)– colonize habitat (在棲息處殖民) and capture food A large gut (腸腔) with a single opening Tentacles (觸手) contains nematocyst剌絲囊 Polyp (螅型體) or medusa (水母體) Obelia Molluscs (軟體動物) Unsegmented (沒有分節) body Bilateral symmetrical (左右對稱) Body consisted of anterior head (頭), ventral muscular foot (足) and a dorsal visceral mass (內臟團). Body is surrounded by mantle (套膜) sheltered in one or more calcareous shells (鈣質殼，殼可以是單殼或雙殼). Example: Snail Gastropod – 腹足綱 Habitat – terrestrial (陸生) 1. Spirally coiled shell (螺旋形殼) 2. Large and broad foot (闊大的足) 3. Rasping (銼刀型) radula (舌齒) for scraping (刮出) algae 4. Eyes at tentacles (觸角末端有眼) 5. Cover sealing (有蓋封密) 6. Protective colouration (保護色) Bivalve (雙殼綱) – Mussel 貽貝 1. Laterally flattened (側面扁平) Habitat – rocky shore (岩岸) 2. Hard calcareous shell of two valves (兩片鈣質貝殼) - for protection (保護) and _____ 3. Hinge ligament (蝶絞韌帶) 4. Byssal threads (足絲) 5. Gills (鰓) – for gaseous exchange and filtering feeding (濾食性) 6. Inhalent (入水管) and exhalent siphon (出水管 Clam (蛤) – wedge-shape muscular foot (斧足) Annelids (環節動物) Bilaterally symmetrical (左右對稱) ，streamlined shaped (流線形) segmented (分節) Has chaetae (剛毛) for anchorage (固定身體) during burrowing (挖掘泥土) Has clitellum (環帶) Examples: earthworm (蚯蚓), leech(水蛭/螞蟥) and bristleworm (沙蟲) Metameric segmentation身體分節 1.allows specialization in certain segments without interference from others (某些體節可特化, 不受其他體節干擾) 2. Allows division of labour (不同的體節可負責某些特定的功能) 3. Division of muscular body wall into blocks, different parts of body can move independently (體壁的肌肉可分成數段, 每段可獨立移動) Arthropods(節肢動物) Segmented body (身體分節) with jointed appendages (附肢也分節) Bilatera