Table 4.

Self-explanatory table of a comparison of selected sperm traits of the five vertebrate classes.

Sperm Trait	Pisces (Teleosts)	Amphibia (Anura)	Reptilia	Aves	Mammalia (Selected)
Sperm concentration	Very high > 10 billion/ml	170 M–1.5 billion/mmillion/mL	Too little information	High, variable (commonly > 1billion/mL	Low to high (40 M–3 billion/mL)
Sperm structure	Small simple, round	Filiform head, small	Filiform, longest	Filiform head, large mid-	Very short to long
	to oval head, small	midpiece, few	sperm among verte-	piece, few mitochondria	heads in rodents,
	Midpiece (3–5 mitochondria, flagellum	mitochondria	brates, longest midpiece	long midpiece	midpiece small with 6
	simple axoneme (9 + 2)	Often undulating	piece, 9 + 9 + 2 tail	9 + 9 + 2 tail	to 300 mitochondria
		Membrane 9 + 2 axoneme			Tail 9 + 9 + 2 tail
	No acrosome	Acrosome cap	Acrosome cap	Small acrosome	Acrosome cap 40 to 70% head cover
Normal Sperm morphology (%)	High, > 80	High, > 80	High, > 80	Variable (low to high)	Variable (low to high) 15–90
Sperm Motility (%)	High, > 75%	13–60	Too little information		Low to high (15 to 90)
Sperm Progresson (%) (STR)	High, > 80	High, >80	High, 80	Variable (75–95)	Variable (15–90)
Sperm Velocity (VCL, µm/s)	110–350	15–60	60–80	70 to 250	(60–400)
Sperm Linearity	High in marine, >80	40–75	60–80	30–98	Low to high (40–85)
Vitality (%)	>80	>80	>80	>80	15–95
DNA fragmentation (%)	Mostly < 10	Too little information	Too little information	Mostly < 5	Mostly < 10