WILMINGTON, Del. — It might be hard for stationery sea creatures to defend themselves, but at least one kind of sea sponge can deploy a chemical shield.
Researchers at the University of Delaware found that the encrusting sponge, or crambe crambe, is able to spew out toxic cells that envelope the organism and dissuade predators.
"It's like a volcano," said Eva Ternon, the post-doctoral researcher, explaining how chemicals erupt from the place where the sponge is attached to its host.
Although the chemical haze is invisible in the ocean, it looks a little bit orange when it is concentrated around the excretion zone in the lab, she said.
When its distributed around the sponge, Ternon called it a chemical halo — but it's a pretty aggressive halo.
The embryos of sea squid can't develop when they are in the sponges' chemical zone, she said.
The sponges naturally send off a low, steady flow of chemicals, but when they are touched they increase their flow by a wide margin. That suggests that it's a defense mechanism, Ternon said.
This means that the encrusting sponge, which lives in the Mediterranean, can join some of the more notable sea creatures that respond to potential danger in unusual ways.
The balloon fish, of course, inflates its body and sticks up its spikes when confronted with a predator – it is probably one of the most widely recognized marine defense mechanisms.
It is not the most interesting, though. Sea cucumbers can voluntarily explode and spray predators with their internal organs, according to Ross Piper's 2007 book, Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals.
Even more interesting, that defense mechanism doesn't kill the cucumber — their bodies can regenerate. And that's not the only trick in their book. They can also send out chemicals and sticky tubules from their anuses to ensnare an encroaching animal, according to Piper.
Ternon's paper on the encrusting sponge, which she worked on with researchers from other universities, is the first to explore the sponges' chemical shield.
"It's really complex," she said, adding it needs to be studied further.
The research that went into this paper took about three years, Ternon said, and the chemicals that were found coming from the sponges could, eventually, contribute to cancer medications.
It's still early, though.
Chemicals that are found in sea sponges have long been used by pharmaceutical companies, but until now the sponges had to be killed to extract their chemical compounds, Ternon said. That's one of the things that prompted the research — she wanted to see if there was a way to use the chemicals without killing the sponges.
Follow Saranac Hale Spencer on Twitter: @SSpencerTNJ