Difference between Cetacea and Sirenia?

Dear aspirant here's the difference between Cetacea and Sirenia

Cetacea

1. Size:

Some attain a colossal size.

2. Habitat

Marine forms. Larger species prefer open sea, while smaller forms live in plenty in estuaries and river.

3. Habit

Carnivorous and predaceous ani­mals.

4. Hairs:

Absent, except a few bristles around the muzzle which may also be absent in many whales.

5. Caudal fin:

Horizontally expanded which is usually divided into ‘flukes’.­

6. Dorsal fin:

An adipose dorsal fin is present.

7. Eyes:

Small and devoid of third eyelid.

8. Nostrils:

Nasal aperture present on the fore­ head as single or double blowhole is usually shifted to the dorsal side of the head. Valvular arrangement is highly developed.

9. Mammae:

Mostly absent, vestige may be present in foetus.

Sirenia

1. Size:

Comparatively small.

2. Habitat

Live in sea near coast, also available

3. Habit:

Herbivorous and feed on aquatic.

4. Hairs:

Very sparse.

5. Caudal fin:

Horizontally flattened, either roun­ded or rhomboidal in outline.

6. Dorsal fin:

Absent.

7. Eyes:

Small and have third eyelid.

8. Nostrils:

Separate from one another and placed on the front of the head. Valves and pads are less developed.

9. Mammae:

Pectoral in position, close behind the forelimbs.

All the best

Hope this helps