Our Observation of the Week is this colorful pair: an Alpheus rapacida snapping shrimp and a Slender Shrimpgoby, seen off of Greece by @rpillon!

“Since I was a child I have loved the sea and, simply, snorkeling,” says Roberto Pillon, an Italian underwater naturalist and photographer. “The bottom of the sea is still a space where nature is the protagonist.” He’s especially interested in fish and echinoderms, and while not a professional researcher, he tells me “Over the years I have had the pleasure of meeting and collaborating with the leading experts in the sector...a simple nature enthusiast today can change our knowledge of nature.”

Last year, Roberto “wandered between the archaeological sites of ancient Greece, [where] I discovered a corner that seemed to be the Red Sea, with a very particular bay full of life…

In this bay, under the eyes of hundreds of people who dive every day, the seabed was littered with fishes and sea urchins never seen before in Greece. Observing live the relationship and collaboration between two such different animals [as those photographed above] is enchanting.

When the Suez Canal opened in 1869, the once separate ecosystems of the Mediterranean and Red Seas met , and since then organisms native to one sea have moved to the other. Most move from the Red Sea to the Mediterranean, a process called Lessepsian migration. The slender shrimpgoby (also known as Mertens’ prawn-goby), is native to the Red Sea and the Indo-Pacific region, and was first discovered in the Mediterranean in 2008, off of Turkey - likely due to Lessepsian migration, but it could have also traveled in the ballast of ships. Roberto’s photo here represents the first record of it in Greece’s waters, as well as the furthest west it has ever been recorded in the Mediterranean.

As its common name suggests, this fish partners up with shrimp (in the Snapping Shrimp family), and they form a mutualistic relationship. The shrimp builds and maintains a burrow in which the goby can hide, and the goby keeps watch for predators that might sneak up on the shrimp, which has poor eyesight. Scott Michael wrote an in-depth article about this pairing, and he says “when [the shrimp] leaves the burrow it keeps in contact with the vigilant Goby. It does this by placing one of its antennae on the fish. (This antennal contact is the critical line of communication between the two animals.)” The species of shrimp in the photo, by the way, is also a migrant from the Red Sea.

Roberto (above) says that “for me, iNaturalist is a companion that reminds me of my underwater world in the very long periods in which I have to live outside my habitat.”

- by Tony Iwane. Some quotes have been edited for clarity.

- You can read a published record of this observation in Mediterranean Marine Science (see page 648). [PDF]

- David Attenborough narrates this video about the relationship between goby and shrimp.

Our Observation of the Week is this awesome Red-lined Bubble Snail, seen off of Australia by @belairjo! 

Sure, this blog post is about a marine snail, but the observer became interested in nature photography when photographing a bird. “When zooming in for a photograph of a Kookaburra in my garden,” recalls Joanne Zerafa. “I loved being able to see the finer details and felt a sense of connection to the animal, as if I could experience the world from their perspective.” 

Joanne spends much of her current nature photography time participating in citizen science, “tracking the presence of species, particularly the east coast population of Australian Grey Nurse Sharks who are critically endangered.” Individual sharks can be identified by their markings, so getting photos of them is really helpful. 

She came across the snail you see above while on a dive with Feet First Dive, and it was spotted by divemaster Casey Hambrecht. “[This species] is a favourite in our region,” says Joanne. “You’d think that their neon mantle would make them easy to find, but due to their small size, it takes a keen observer to find them.”

Recognizable by that distinctive lined shell and the large, blue-outlined margin of its foot (and don’t forget that pair of black eye spots!), the red-lined bubble snail ranges throughout the Indo-Pacific region and is generally found in intertidal areas, but can be found subtidally. It is believed to feed mainly on polychaete worms.

Joanne (above, on a dive), tells me “I love how iNaturalist facilitates the research that citizen scientists carry out via their photography. Our observations are logged, species identified by scientists and enthusiasts and added to projects for further research. 

iNaturalist has transformed the way I feel about the changing climate. Instead of feeling helpless, I feel like I am contributing to the provision of knowledge that could assist with establishing policies and protections that environments will need for their survival.

- by Tony Iwane

- Slugs and snails rasp away at their food with their radula. Check out plate 3 here for some SEM images of a Red-lined Bubble Snail’s crazy radula.

- A Red-lined Bubble Snail makes its way across some algae in this video.