RE: NANFA--Fundulus dispar

Hoover, Jan J WES (HOOVERJ_at_wes.army.mil)
Mon, 5 Jun 2000 15:54:42 -0500

Fundulus eggs seem destined for prolonged prehatching periods. Dessicated
eggs of freshwater species take longer to hatch because dessication slows
down embryo development. Eggs of estuarine killies often take 10-14 days to
hatch. Spawning is tied in with a semi-lunar cycle: eggs are laid and hatch
on new and full moon spring tides. To my knowledge, semilunar periodicity
is not been documented in freshwater killies. Is it possible that prolonged
hatching times of freshwater species are holdovers from marine ancestors?

-----Original Message-----
From: Mark B
Sent: Monday, June 05, 2000 3:15 PM
To: nanfa_at_aquaria.net
Subject: Re: NANFA--Fundulus dispar

At 1:28 PM -0400 6/5/00, Michiganfish_at_aol.com wrote:
>Mark
>My tanks are about 60 F. I've watched the eggs under a microscope and they
>have just developed that slow . I thought it was odd because This spring
the
>Rainbow, Greenside, dusky, and Iowa darters all took 6 to 8 days. N.
>Redbelly and Fatheads took 6 days and Rosyface shiners that just spawned
took
>less then 4 days. I guess I just haven't worked with Killis in awhile.

Yeah, I think even NA killies like it warm for breeding and hatching. But
I could be mistaken. From other comments, sounds like maybe the NA killies
have some interesting strategies to be successful with low egg production
and adaptation to changing environmental conditions. In a temperate
climate, temperature, water level, and plant cover change continuously
thoughout the year, especially in the spring and summer. It may be
advantageous to have delayed hatching of some of the eggs. Just wild
speculation!

Mark Binkley
Columbus Ohio USA <))><
mbinkley_at_earthling.net

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