Question

What characteristics are common to fish?

Answer 1

Fish is an aquatic gill breathing vertebrates with paired jaw, and paired girdles associated with pectoral and pelvic fins.

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Explanation:

Fishes are included under Phylum Chordata, Superclass Pisces.

Fishes may generally possess mesodermal scaleson skin.

External nares are present but they open in small pits (thus internal nares are absent),

Internal ears are there each with three semicircular canals but external ears absent.

Lateral line sensory organ is present.

Deoxygenated blood from the body converges to heart and it is then pumped towards gills for gaseous exchange. Oxygenated blood flows towards body tissues from gills. Such a heart is called venous heart .

http://web.utk.edu/~rstrange/wfs550/html-con-pages/l-heart.html

Fishes are highly diversified; many are extinct (Class Placodermi) while living fishes are normally studied under two headings: bony fish and cartilagenous fish.