reproductive strategies in the marine world

REPRODUCTIVE STRATEGIES
IN THE MARINE WORLD
Betty Staugler, Florida Sea Grant Agent - UF/IFAS Extension Charlotte County
With the exception of humans, and our spayed and
neutered pet friends, survival and passing on genes
through reproduction are all encompassing for the
remainder of the animal kingdom, the marine environment included. Marine organisms have a fascinating
array of reproductive
behavior patterns. They
can be pelagic spawners,
benthic spawners, nest
spawners, or bearers of
live young. They may be
guarders, non-guarders,
or brood hiders. Further
they may have elaborate
courtship or no
courtship.
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occurs in late summer or early fall on dark nights (new
moon particularly) between 10:00pm and 3:00am when
eggs and sperm are released into the water column
(pelagic spawning). Such spawning behavior is likely an
adaptation to avoid egg predation.
Another fish with an
interesting reproduction
strategy is the gulf killifish, a
fairly common baitfish. There
are fifteen species of killifish
found in Florida and although
most are freshwater fish, the
gulf killifish, as its name
implies is a saltwater species.
The majority of saltwater fish
species reproduce through
Take a goliath grouper
external fertilization. Killifish
for instance, adults
however reproduce through
generally show a strong
internal fertilization and then
Goliath Grouper—FSG Image
site preference and move
the female lays eggs.
very little; however they
However she doesn’t just
are known to travel one hundred miles or more to reach
deposit them anywhere. She lays them in muddy
spawning aggregation sites. Most of the known
sediment at the water’s edge during a flood tide. When
spawning aggregations
the water recedes the eggs
are off of southwest
incubate in the mud until the
Florida, but additional
next flood tide at which time
aggregations have been
they hatch. Interestingly,
observed off of Florida’s
killifish in freshwater systems
central east coast.
use a similar approach. They
Researchers and
lay eggs in the mud within a
volunteer dive groups
small puddle of water. The
have observed various
puddle dries, the eggs
goliath grouper color
incubate, and when the next
changes associated with
rain rehydrates the ground,
spawning aggregations
the eggs hatch.
such as dark, bi-color,
and white/ gray color
Fish are not the only marine
phases. They have also
animals with interesting
Gulf Killifish—FL Museum of Nat. History Image
noted behaviors
reproduction strategies,
associated with goliath
invertebrates (animals that
grouper spawning aggregations that include pairing or
lack a backbone) also exhibit unique strategies. Take
(Continued on page 2)
grouping, stacking, and/or barking/bellowing. Spawning
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REPRODUCTION IN MARINE WORLD
July 3, 2014
tunicates for example. Tunicate are those gelatinous
cean (related to shrimp and crabs). What is absolutely
globs that are often found on mangrove roots, encrusting fascinating about barnacles is that although they’re
on seagrass blades or
cemented to structure and
washed up on the beach
don’t move, they do
looking like a softball sized
reproduce through internal
blob of rubber. Tunicates
fertilization. How do they do
are filter feeders, taking
it? Well it turns out,
water in through one
barnacles which are also
siphon, extracting particles
hermaphrodites like the
then expelling the water
tunicates previously
through the second siphon.
mentioned; possess the
Most tunicates are
longest penis relative to their
hermaphrodites, meaning
size in all the animal kingdom.
they possess both male and
Yep, they reach out and
female sexual organs. They
fertilize their neighbor, and
avoid self-fertilization by
when they’re done they
having the eggs and sperm
discard the penis, growing a
Tunicates—FSG Image
mature at different times or
new one when they need to
by having the eggs and
reproduce again.
sperm reject each other.
Tunicates reproduce by
So there you have it, a sneak
releasing sperm into the
peek into some interesting
water column. The sperm
reproduction strategies
then enters another
employed by a few of our
tunicate through the siphon
more remarkable marine
with incoming water, and
species.
the eggs are then fertilized.
Probably one of the most
noteworthy reproduction
strategies is that of the
lowly barnacle. Barnacles
are truly oddballs. They
look more like a mollusk,
but are instead a crusta-
Barnacles—FSG Image
Sources:
Rocha, R. Tunicates are Cool. PPT. Smithsonian Institute
Marine Scene, Volume 50-2. written by John Stevely, Florida Sea Grant Agent,
University of Florida-IFAS Manatee County Extension.
BETTY STAUGLER
Florida Sea Grant Agent
[email protected]
UF/IFAS EXTENSION CHARLOTTE COUNTY
25550 Harbor View Road, Suite 3 - Port Charlotte, Florida 33980
941.764.4340 - 941.764.4343 (fax) - http://charlotte.ifas.ufl.edu