一、棲息環境與分布
海豹是典型的海洋哺乳動物，主要分布于南北極及溫帶海域，部分種類如斑海豹可延伸至中國渤海等亞北極海域。棲息地類型多樣，包括浮冰區、巖礁海岸及沙洲，其中北極環斑海豹依賴海冰繁殖，而斑海豹則選擇遼東灣冬季結冰區產仔。不同種類對環境的適應性差異顯著，如威德爾海豹能長期棲息于南極固定冰區，而港海豹則偏好溫帶無冰海岸。

二、生理適應特征
海豹具有高度特化的生理結構：
1.體溫調節：厚達60mm的皮下脂肪層兼具保溫和能量儲備功能，血管系統通過四肢末端收縮減少熱量散失。
2.潛水能力：可下潛至550米（帝企鵝數據誤植，實際為海豹），閉氣時間達43分鐘，血液和肌肉中高濃度肌紅蛋白增強氧氣儲存。
3.運動器官：流線型身體配合鰭狀肢，游泳時速達27公里；陸上移動依賴腹部滑行或五趾肢爬行。
三、食性與捕食行為
海豹為肉食性，食譜包括魚類（如鱈魚）、頭足類（烏賊）及甲殼類（磷蝦），日攝食量占體重5%-8%。捕食策略因種類而異：環斑海豹利用冰層呼吸孔伏擊魚類，而豹海豹則主動追擊獵物。部分種類如斑海豹具有季節性洄游習性，追蹤魚群資源。
四、繁殖與育幼
繁殖周期呈現顯著物種差異：
1.交配行為：雄性通過爭斗確立交配權，勝利者在水中完成交配；斑海豹繁殖期為1-2月，妊娠期約9個月。https://weibo.com/
https://weibo.com/ttarticle/p/show?id=2309405166885179359453
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2.育兒策略：母海豹在浮冰或陸地產單胎幼崽，哺乳期1個月（斑海豹）至數周（港海豹），乳汁脂肪含量高達40%-50%促進幼崽快速增厚脂肪層。
3.幼崽發育：新生斑海豹幼崽披白色胎毛（2周后脫落），6周內學會游泳，3-4年性成熟。
五、社會行為與交流
海豹社會結構相對松散，非繁殖期多獨居，繁殖季形成臨時集群。通訊方式包括：
1.聲音信號：水下通過低頻吼叫宣示領地，威德爾海豹能發出復雜聲吶導航。
2.視覺標記：斑海豹通過體表斑點識別個體，雄性髯海豹用鼻球結構展示優勢地位。
3.學習能力：人工飼養個體可掌握簡單指令，野生個體表現出工具使用行為（如用石塊破冰）。
六、物種多樣性差異
現存約18種海豹，主要分為：
1.真海豹科：無外耳，后肢不能前彎（如斑海豹、灰海豹），陸地移動笨拙。
2.海獅科：具外耳，四肢靈活可行走（如加州海獅），社會性更強。
3.特殊適應種：食蟹海豹以磷蝦為主食，豹海豹可捕食其他海豹，象海豹潛水深度紀錄達2388米。