I’m one of those divers. One of those that like to just stay 10 minutes exploring the same rock looking for all the funny looking tiny critters. Oh! Are there sharks around? Let me first finish taking this photo of this nudibranch! What? A huge school of jacks is circling us? Cool but have you seen this new shrimp we’ve never seen before? Yeah, that kind of diver.

If you are like me you will LOVE Loreto.

It’s funny here. Surprisingly for many of us, Loreto’s waters are not the same all through the year. Not at all. Seasons drastically differ in temperature, plankton production, weather etc. This has forced the marine life to adapt and make the most of the ideal conditions when they come. For us, macro lovers, this tend to be winter and spring time.

During these months where the water is colder and richer with nutrients, some of the small life thrives, like nudibranchs, snails and flat worms.

These guys come in the thousands at that time. The invertebrate biodiversity in Loreto is the largest of all Baja Sur according to the researches done by the University of Baja California Sur (UABS) and it shows.

Whereas nudibranches and flat works can be found all year round, they are obviously more obvious and easy to find in winter and spring, and they come in greater variety as well.

The most common types of nudis are the Tambja family, Felimare californiensis, Chromodoris marislae, Felimare agassizii, Felimida baumani, Felimida norrisi, several Flabellinas, to name some, but there are dozens other.

In spring, most of these nudis come out for mating, and you will find them “at it” very often. About this time of the year, another big attraction is finding the huge Tiger nudibranch (Roboastra tigris). This absolute behemoth can grow as large as 30 cm and feeds on all the other smaller nudibranchs that it can find.

Among the flat worms, the most beautiful one is the endemic Speckled flatworm (Pseudocerus bajae). It is luckily the easiest to find too. At the beginning of the season it can be found under rocks or well hidden, but in spring they come out and form mating aggregations, sometimes of a dozen!

An incredible variety of flatworms can be found all year round under the rocks.

Snails behave in a similar fashion. The most remarkable examples would be the Mushroom snail (Tylodina fungina) that feeds on yellow sponge, and the wonderful Apricot snail (Berthellina).

The only exception to this winter-spring seasonality would be the sea hare family, that are more commonly found in summer in large groups over sand or rubble.

Besides nudis and squishy stuff, then there are also gobys, blennys and the crustaceans, that excel specially on shrimps and crabs. The variety in these ones is so vast, that it will probably be features in another article. But know that there are thousands and most of the times I keep finding new ones!