Big Sponges
By Dr. Joe Richardson
Winter-time beachcombing on Tybee Island can sometimes be the most
productive season of the year, especially for finding some of the larger
specimens. During winter, I’ll look up and down the beach along the high
tide line searching for large “clumps.” They are easier to spot during winter
because there are fewer chairs, umbrellas and bodies out there. These
“clumps” might be large pieces of driftwood; or tumbleweed-like mats of
tangled Sea Whips, old rope, seaweed, and marsh grass; or they might be
large Sponges that have washed ashore. I think it is because the rougher
seas during winter rip these larger animals off the deep hard-bottom reefs
where they grow attached.
A few years ago, I met a fellow who watches most every sunrise from the
beach during the winter. Joe and his wife come from Indiana each year to
spend the winter on Tybee, and he is good at finding those large sponges. So
I’m always excited to get a text message from “Indiana Joe” because I know
it will include a picture of a big sponge that has washed up.
I’ve seen a variety of big sponges washed up on Tybee’s beach over the
years. Basket or Vase Sponges can be as large as a bucket, and if they are
fairly fresh they might be golden or slightly crimson colored. Highly branched
Finger Sponges can be close to two feet tall, and may be golden or orange.
26 TYBEE BEACHCOMBER | FEB 2018
Hollow Tubular Sponges with large holes scattered along the sides are
usually brown, but if they have recently washed ashore, you might find small
brittle stars (like skinny starfish) still living inside the tubes. Usually not as
large, but certainly the brightest colored sponge, is the highly branched Red
Beard Sponge that can be bright red or orange.
While alive, many sponges have bright colors, but those pigments tend to
be unstable chemicals, so when a sponge dies, the color soon disappears.
More often than not, by the time it washes ashore and sits on the beach a
few days, the sponge will be brown or beige. Sponges tend to produce a
wide variety of strange chemicals that make them taste and smell bad, and
these noxious chemicals serve as a means of chemical defense to deter
other animals from eating them. As with many other poisonous or noxious
animals and plants relying on chemical defense, they tend to also produce
bright colors as a means of advertising or warning potential predators that
they will be sorry if they take a bite out of them. So you might also notice that
these large sponges cast up on the beach can be pretty stinky!
Sponges are an ancient group of animals. Because of their structural
simplicity, some zoologists prefer to place them in their own group
somewhere between single-celled protozoans and true multi-celled
members of the animal kingdom.
Dr. Joe Richardson is a retired marine science professor with 35+ years of
research and teaching experience along GA and the southeastern coast and
Bahamas. Besides research, he conducts Tybee Beach Ecology Trips year
round (www.TybeeBeachEcology.com) and frequently posts pictures of what
they are finding on his Tybee Beach Ecology Trips Facebook page.
Beach Walks
with Dr. Joe