Category: nudinotes

SPECIOUS SEA SLUGS Specious: misleading in appearance, superficially plausible but actually incorrect. Cryptics Mimics Variations & Morphs Most divers just enjoy their recreation with little exposure to, or even interest in, the scientific process. They take pleasure in what they see and find, often recording those finds on a camera. There comes a time though

Above: Doto rosacea, displaying all the standard Dendronotina characteristics –  large rhinophoral sheaths, branching appendages arranged down the lateral sides of the notum and feeding upon hydroids. DELVING INTO DENDRONOTINIDS If you have been reading the NudiNotes and Book Chapters that have been posted so far on NudibranchDomain you will have seen the word dendronotinids

NUDIBRANCH GILL GUARDING Shell-less but not defenceless The sea is full of hungry mouths, many many hungry mouths either lying patiently in ambush or constantly on the move, in all directions, hunting for any opportunity to take a bite and feed. The last thing any animal needs is to have some attractive piece of their

THE ALLURING ARDEADORIS – Some examples of the genus Some nudibranchs are both a delight to find and undemanding to photograph. Every time I happen across a species of Ardeadoris, concerns of composition and exposure just melt away as I enjoy myself, capturing their image in all their glory. Here we have a group of

RUDIE NUDIES – The Mating Game Nudibranch aficionados, those individuals who spend their time searching the ocean floor for the slimy objects of their desire, will at sometime or other have come across pairs of them conjugating. Because they fertilise internally (with a few exceptions) they must orient themselves to bring the appropriate parts into

A generalized table indicating the diet of the major sea slug groups. Click the image below to view the full table (opens in a Google Sheet in a separate tab) About the table The above is just an image for navigation purposes and will not show the latest revisions/corrections. Use the link to access the

Thuridilla Entanglements Some observations on Thuridilla mating Recently (Feb, 2022) I captured an image of a pair of our Thuridilla cf. splendens apparently engaging in the act of hypodermic insemination (shown above). The image shows both specimens of the pair with a swollen everted penis pushed up against the external surface, posteriorly on the right

Plocamopherus ceylonicus displaying the four papilla-mounted bioluminescent globes arranged around the vulnerable gill. ILLUMINATION ENLIGHTENMENT Bioluminescence in Nudibranchs Species of the humble sea slug can possess unusual and extraordinary capabilities such as autotomy, zooxanthellae hosting, kleptoplasty, exploitation of their prey’s defences through nematocyst sequestration and toxin accumulation, not to mention some incredible host mimicking. Another,

CERATA Part 2 – The Multiple Functions In Part 1, an overview of cerata was given together with some examples of what are, and what are not, considered to be cerata and which sea slug taxa possess them. A list of their diverse roles was included. Here in Part 2 those roles (excluding defence –

CERATA: The Multifunctional “Fingers” of Sea Slugs Part 1 – Introduction The term cerata (singular: ceras) is most often associated with the processes that arise from the dorsum of the Aeolidina – the aeolid nudibranchs. However, it is also commonly applied to the processes found on the dorsum of some of the Sacoglossa sea slugs

HUNTER SEA SLUGS Brittle Stars, Worms, Bivalves and Crustaceans as prey In this NudiNote on sea slug feeding we look at those that are hunters, those sea slugs that actively track down their mobile animal prey as opposed to the majority of sea slugs that are consumers of sessile, attached (or drifting) prey. Rather than

Ceratosoma trilobatum – Ceratosoma tenue – Ceratosoma gracillimum In No. 3 of this series there are actually 3 species to compare. These 3 are quite often confused and there are good reasons for that confusion. All were described not last century but the century before – the 19th century. All can present in different colour

VEXATIOUS VARIABILITY – No. 3 Goniobranchus splendidus Goniobranchus splendidus is a common and conspicuous species of nudibranch, though endemic to the east coast of Australia, from southern New South Wales to central Queensland. It exhibits variation in presentation, some of those attributed and limited to specific regions within its range.     Variation exists in

More Colonial Consumers Sea Slugs that graze upon Ascidians, Bryozoans and Entoprocts It’s been mentioned before that the feeding preferences of sea slugs, across the entire group, encompass an extremely diverse range of food types, but conversely, each species usually has an extremely specific diet. In this NudiNote, three other phyla from the Animal Kingdom,

VEXATIOUS VARIABILITY – No. 2 Goniobranchus geometricus Goniobranchus geometricus, to the uninitiated, can appear very much like a phyllidiid nudibranch if the gill is not displayed – all black and white and lumpy. However there are, from time to time, other variations in the mantle appearance that make you take a second look. All though

VEXATIOUS VARIABILITY – No. 1 Hypselodoris jacksoni There are a number of common species of nudibranch that can exhibit a variability of presentation. These differences can sometimes be put down to geographical location but more than often, not necessarily so. At first it can be confusing but once it is realised that the variations belong

“The Sting’s the Thing” Sea Slug Predators of Anemones and Hydroids Have you ever inadvertently brushed past a stinging hydroid during a dive and some small part of your skin, being exposed, receives a searing sting? Or perhaps you have been enjoying the surf and a bluebottle’s tentacles have wrapped around your arm or chest

Phyllidiid Suctorial Feeding We are occasionally fortunate enough to encounter and record a nudibranch feeding, that is, to actually see that they are feeding, because most often the process is hidden from us beneath them. In those instances, with the sponge-feeders, the buccal mass can be seen protruding and pressed against the sponge tissue that

SPONGIVORES – The Sponge Eaters Sponges (Phylum Porifera) are one of simplest and oldest of multicellular animals. They have the least complex body form of the multicellular animals. Only a few specialist predators are known to be exclusively spongivores, that is, to have a sponge diet and these are disproportionally represented in the sea slugs.

Slugivores – Sea Slugs That Prey On Sea Slugs The great majority of sea slug species are carnivorous, meaning they prey on animal life rather than plant life. It is often not appreciated that sponges, bryozoans and hydroids etc. although primitive life forms, and appear to grow like plants, are animal life forms all the

  Hitchin’ a Ride on the Sea Slug Train It is often said there is no such thing as a free meal, but what about a free ride to collect your meal? One sees sea slugs on many sessile invertebrates either feeding or traversing but only occasionally does one see invertebrates upon sea slugs. In

  The Algae Grazers (Header image above – Petalifera ramosa) It has long been established that the algae are the base upon which the marine food web is built and sustained. Algae are an important food source for numerous marine animals across many different phyla and the sea slugs are no exception. (Algae, in the

Many people are surprised to learn that some nudibranch sea slugs are actually corallivorous, that is they feed upon corals. Those that keep corals in aquariums however know only too well the havoc certain nudibranchs can cause particular corals. Corals don’t look to be particularly appetising but a little explanation of their anatomy will help.

The Gastropteridae are cephalaspideans or head-shield slugs. It would appear that their “main claim to fame”, bright and dramatic colouration of many aside, revolves around the ability and propensity of many to swim by flapping their parapodia. This behaviour has led to them receiving the common name of “bat-winged slugs”. Behaviour, especially one so demonstrative

Across the entire group, the sea slugs have an extremely diverse source of food types, but conversely, each species usually has an extremely specific diet restricted in many cases to one or only few, usually closely related, prey species. A list of the animal types preyed upon reveals that all the major invertebrate phyla are

Mexichromis pusilla – Verconia varians In No. 2 of this series Mexichromis pusilla (Bergh, 1874) and Verconia varians (Pease,1871) will be discussed. Both species were described back in the 19th century and have gone through a couple of name changes. The original genus for both was Chromodoris. There had been much confusion in the literature

Miamira moloch is a large to very large nudibranch of the Chromdorididae Family. It was first described as Ceratosoma moloch in 1988 by Rudman from two specimens, one collected from Heron Island, Central Queensland and the other from North Stradbroke Island, Southern Queensland. At first glance the specimens in the above montage all appear to

When you don’t possess true eyes to recognise the shape of things, to see where you’re going, or what’s coming, then you must certainly have some other highly developed sense to survive. Living in a medium that has thousands of different compounds dissolved or suspended in it, a virtual soup of chemicals, released either intentionally

The Aglajidae are a carnivorous group of headshield sea slugs that actively hunt their prey. They are mostly fast moving in order to capture other sea slugs and polychaete worms. They are well-adapted for the task with clusters of sensory bristles located on the front of their broad headshield, on mounds both sides of the

Sometimes when reviewing images post-dive it’s easy to overlook an uncommon species if it has a similar appearance to a species that is frequently sighted. We know the common one well but have forgotten about the rarer one that looks similar – The Lookalike. This NudiNote will discuss a not-so-common species – Verconia decussata (Risbec,1928)

We all know about the rhinophores of the true nudibranchs – those highly developed chemical-detecting “antennae” located anteriorly on their “head”. Even sea slugs other than the true nudibranchs such as the sea hares, and the side-gilled pleurobranchs have rhinophores. These though are tubes formed by longitudinal rolling rather than the solid form of the

Tenellia sibogae (or Trinchesia sibogae, depending on whose taxonomy you follow) is usually sighted upon its food – arborescent hydroids of the Sertularella genus (usually identified as Sertularella diaphanous or Sertularella quadridens). If you are searching for sea slugs and spot this characteristic looking hydroid it is definitely worth your time to search through it

Hexabranchus The name says it all. It has six gills – Hexabranchus. The family and genus hold six separate species. The species Hexabranchus sanguineus (sanguineus – blood-coloured) was originally described from the Red Sea. Specimens of that species from that region are not red and white mottled as in the images posted here but are

UNIQUELY UNITED BUT DECEPTIVE DISPLAY The Suctorial Feeding Porostomata Nudibranchs In a previous NudiNote – The Little Scraper – the radula of sea slugs was discussed. Mention was also made of those sea slugs that do not possess a radula. Among the dorid nudibranchs in particular, the radula has only been lost once along their

Autotomy – the Self Sacrifice Defence   The ability to cast off a particular section of their anatomy, in order to facilitate escape from a predator, is possessed by a wide range of animals. Although the phenomenon, even in the Mollusca, had been recognized previously the term wasn’t coined until 1883 by Leon Fredericq as

VIVA VARIATION Change is upsetting    Repetition is tedious.       Three cheers for variation! Mason Cooley Across all of the Sea Slugs there is an almost endless amount of variation. Different shapes, sizes, textures, patterns and colours. We aficionados of the Sea Slugs enjoy all of that variation for it gives us many

The Little Scraper Nearly all the sea slugs, just like nearly all the molluscs (except the bivalves), possess a radula in the buccal cavity for feeding. The radula is used not unlike a combination of teeth and tongue to rasp at, puncture, slash or grip the prey for ingestion. Salivary glands assist the action of

Sorting out the True Nudibranchs   The Nudibranchs are but one order, the Nudibranchia, in the informal group that we refer to under the umbrella of Sea Slugs although common and popular usage has seen the term Nudibranchs used incorrectly to refer to all the sea slugs in general. This NudiNote is concerned just with

THE EXCEPTION TO “THE RULE” Phyllodesmium acanthorhinum is a rarely sighted, though widely distributed, species first recorded from Okinawa by Bob Bolland in 1987. The 15 mm long specimen pictured here was found in the Mooloolah River, southern Queensland, Australia in 3 m of water. It had long been thought that species of Phyllodesmium only

CONGRESS ON CODIUM All of the sea slugs in the Sacoglossa order are herbivorous, well nearly all, a very few prey on the eggs of other sea slugs. However, that great majority that feed on plants do so by puncturing the cell walls of algae and sucking out the contents. The sacoglossans are a very

The true nudibranchs are divided into two suborders – Suborder Cladobranchia and Suborder Doridoidea. Without doubt the most noticeable external difference between the two is in the appearance of the gills. Here we must generalise of course with the dorids having a circle of gill branches around the anus, sometimes presenting as an arc or

Trying to decide to which genus a phyllidiid nudibranch belongs from a photo can be a task of some difficulty. There are some external features that can be used, but these are not always easily observed. Here is a rough external guide boiled down to the basics: Phyllidia – Oral tentacles separate; rhinophores cream, yellow or