**4.1 Cetaceans**

Cetaceans are a cosmopolitan and diverse clade of aquatic mammals; they include whales, dolphins, and porpoises. They are flesh-eating (carnivorous) and most of them are found in the oceans.

Cetaceans are differed in size and weight, the length ranged from 1 m in Maui's dolphin to 29.9 m as in blue whale, and the weight ranged from 50 kg to 173,000 kg.

*4.1.1 Whales*

• There are now 15 species (**Figure 1**) and around 89 extant species [3].
