Magnificent Chromodoris by Marc Broadbent DSC-RX100M4: 1/1000, F11, ISO100

This nudibranch is found in the central area of the Indo-Pacific region from Indonesia and the Philippines to New Guinea and Eastern Australia. It can reach a maximum length of 60 mm. The body is elongated by a foot which is distinct from the upper body by a skirt like mantle hiding partially the foot. The branched gills and the rhinophores are orange and can be withdrawn into specific pockets under the skin in case of danger.

Co's Chromodris (Goniobranchus coi) by Marc Broadbent DSC-RX100M4: 1/500, F8, ISO200

Also known as Co's Goniobranchus, Dorid Nudibranch, Elegant Chromodoris, Nudibranch. Found singly or in pairs amongst rubble and sandy areas over coral and rocky reefs. They are 6cm long and feed on the sponge Chelonaplysilla violacea. They are widespread in Indo-West Pacific in depths of 5 - 25m. Nudibranch, meaning "naked gills" are molluscs without a hard shell. All opisthobranchs are hermaphrodites. These beautiful slugs are usually brilliantly coloured and this in itself can act as a deterrent against predators. Some nudibranchs secrete acid from stinging cells in their tentacles while others secrete acid from cells in their mantle. Nudibranchs are slow moving, can swim or be propelled along either by muscular contraction or by millions of tiny hairs on the bottom of a fleshy 'foot', they have a voracious appetite and feed with a rasp like tongue. Nudibranch lay their eggs in a ribbon effect on the sand, in different colours depending on species.

Suzanne’s Flatworm (Pseudoceros suzzanae) by Marc Broadbent DSC-RX100M4: 1/60, F3.5, ISO80

Fuchsia Flatworms can be 18–48 mm long and they have an enlarged oval shape. The upper surface of the body is fuchsia (hence the common name) with small white dots and two marginal bands red and orange without dots. The color is dark red with the dorsal surface covered by compacted small white dots given the appearance of a brilliant pink surface. This species is widespread in the tropical Indo-Pacific, from the Indonesian Archipelagos to Central Great Barrier Reef in Australia, Palau in Micronesia, Philippines and the islands of Hawaïi.

Crested Nembrotha by Jonathan Broadbent DSC-RX100M4: 1/250, F9, ISO200

Nembrotha cristata is a species of colourful sea slug, a polycerid nudibranch, a marine gastropod mollusk in the family Polyceridae. This species of sea slug is black with green markings; adults are around 50 mm long, and they live on rock or coral reefs in the tropical Indo-West Pacific Ocean, in depths of 3m to 20m. Nembrotha Cristata are also known as Cabbage Nudibranch/Sea Slug/Snail or Cabbage Patch Nudibranch. You can find them on coral, rocky reefs or sandy, rubble bottoms. The Nembrotha Cristata have two Rhinopores which help them to detect food via scent and taste. These are the antenna-like objects on the Nudi's head. They like to feed on coral, sponges and Anemomes and also enjoy Hydroids. They also absorb stings from jelly fish into their skin when feeding on them and this acts as a defense mechanism against predators.

Solar powered Phyllodesmium by Marc Broadbent DSC-RX100M4: 1/250, F9, ISO160

This rare find was found in Lembeh; they can be found from Australia up to Indonesia usually on or next to octocoral and on sand. It can grow up to 14 cm long. Solar powered nudibranch feed on soft corals and they are able to remove the algae intact from the coral’s tissues and store it in their cerata. The intact algae continues to photosynthesize within the cerata and supplies gives the nudibranch an ongoing supply of manufactured sugars. Due to the large surface area of this nudibranch’s cerata they act as solar panels!

Forskal’s Pleurobranch by Marc Broadbent DSC-RX100M4: 1/500, F10, ISO100

Also known as Forskal's Nudibranch, Notoaspidean Sea Slug, Nudibranch, Pleurobranch Sea Slug, Side-gilled Sea Slug. They are found singly or in pairs in shallow waters of lagoons, pools, seagrass beds and reef crests, mostly in Indo West Pacific in depths of 0 - 30m. They feed on ascidians. Varies in colour from place to place. Length - 30cm.

Polyclad Flatworm, Pseudobiceros by Marc Broadbent DSC-RX100M4: 1/100, F4.5, ISO100

Pseudobiceros is one of the largest and can swim by undulating its flexible body – watching a flatworm swim in the water column is quite a sight! This beautiful flatworm looks like the skirt of a Spanish dancer. Nudibranchs move slowly by self-secreting a mat of mucus.

Polyclad Flatworm, Thysanozoon Sp (Gold-Dotted Flatworm) by Marc Broadbent DSC-RX100M4: 1/100, F6.3, ISO100

This nudi has a long body and broad shape. They grow up to 76 mm long. They swim by propelling themselves through the water with a rhythmic undulating motion of the body. This species is widespread in the tropical Indo-Pacific. They are quite common along the external reef in the shallow sub-tidal zone. It can swim by undulating and rhythmically contracting the body margins. It feeds on tunicates, using its mouth and large pharynx to engulf its prey and later regurgitates food pellets containing the calcareous spicules present in their tunics.

Bullock’s Hypselodoris by Marc Broadbent DSC-RX100M4: 1/100, F9, ISO400

Also known as Bullockii Sea Slug, Dorid Nudibranch, Hypselodoris Sea Slug, Nudibranch, Purple Nudi, Purple Nudibranch, Variable Hypselodoris. Found singly or in pairs amongst sand and rubble areas of coral and rocky reefs in the Indo West Pacific at depths of 2 - 30m. They feed on sponges.

Pteraeolidia ianthina (Blue Dragon) by Marc Broadbent DSC-RX100M4: 1/100, F5.6, ISO80

This is a juvenile Pteraeolidia ianthina. Adults show considerable variation in colour with some having tha very white colour form while others are shades of brown and purple. The brown ones all contain specialised branches of the digestive gland which contain microscopic brown algae which they apparently obtain from their food hydroids. However juveniles lack these brown plant cells and so are white. Pteraeolidia ianthina, commonly known as the 'Blue Dragon', is one of a group of remarkable aeolid nudibranchs in harnessing solar energy. Pteraeolidia has evolved a method of capturing and farming microscopic plants (zooxanthellae) in its own body. The plants flourish in this protected environment and as they convert the sun's energy into sugars, they pass a significant proportion on to the nudibranch for its own use. The white animal is a juvenile which as not yet developed its crop of zooxanthellae.

Fireworm (Amphinomidea) by Marc Broadbent DSC-RX100M4: 1/30, 8, ISO400

Amphinomidae can cause great pain if their toxin-coated chaetae are touched or trodden on.

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Diana's Chromodoris

This species is very similar in appearance to Chromodoris lochi. The difference is the broken black lines on its back.
Chromodoris dianae has white gills and rhinophores with distinct yellow-orange tips. Chromodoris dianae can reach a maximum size of 4 cm long,

Phyllodesmium briareum by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Found in western Pacific and Indonesian Archipelago. Phyllodesmium briareum, like other species of Phyllodesmium, feeds on soft corals and is very well camouflaged when crawling over or nestled between the polyps of the soft coral it is feeding on. It is reported to feed on a number of species of briareid soft coral. The rows of brown specks in the photo are one-celled plants [zooxanthellae] which are nurtured in specialised ducts of the aeolid’s digestive gland, where they continue to grow, reproduce and photosynthesise, providing nutrients for the aeolid.

Red Flabellina by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Coryphellina rubrolineata is a relatively large aeolid nudibranch growing to 42 mm. The stretched out body has a sharp end at the tail, the dorsal side is covered with extensions called cerata. The rhinophores are pointed and look like feathers. The oral tentacles are thin, cylindrical and longer than the rhinophores. This species is thought to be widespread in tropical, subtropical and temperate waters in the Indo-Pacific area and also as a migrant species in the Mediterranean Sea. It is also commonly observed on shallow reef or rocky slopes rich in hydroids which represent its main diet.

Blue Velvet Headshield Slug by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Chelidonura varians is a species of small sea slug, a marine opisthobranch gastropod mollusc in the order Cephalaspidea, the headshield slugs. This species has a maximum size of 70 mm. They have well-developed sensory cilia on the anterior edge of the head which are used to find prey. This species lives on reef areas in shallow water lagoons with sandy or muddy bottoms upto 30m in depth.

Hypselodoris tryoni by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Hypselodoris tryoni is a dorid nudibranch. Hypselodoris tryoni reaches at least 60 mm in length and has been observed to raise and lower its head while crawling.

Goniobranchus hintuanensis by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Nembrotha lineolate by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Nembrotha lineolata grows to a length of about 70 mm. The body is slender with a rounded head at one end and a pointed tip to the foot at the other. The exterior of the body is covered with longitudinal wrinkles and there is no sharp demarcation between the dorsal surface and the lateral surfaces. The oral tentacles are thick and long and the large conical rhinophores bear about thirty lamellae and can be retracted. The three large pinnate branchial plumes on the dorsal surface are non-retractile and the anus is located between them.

Chromodoris elisabethina by Marc Broadbent DSC-RX100M4: 1/2000, F11, ISO6400

Chromodoris elisabethina is has a blue or bluish-white background colour and black or dark blue longitudinal lines. Often they have orange or yellow gills and rhinophores and a similarly coloured mantle border the "typical" colour pattern, but the orange border can be somewhat faint, (and apparently submarginal), and the median black line can be replaced by an irregular group of shorter lines. This one was shot with a snood in Lembeh.

Siboga Glossodoris by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Doriprismatica sibogae is very similar in appearance to Doriprismatica atromarginata, but can be distinguished from that species by the intense yellow colour of the mantle and foot. The black mantle edge is separated from the yellow of the back by a white line.

Three-lobed T-Bar nudibranch by Marc Broadbent DSC-RX100M4: 1/30, F8, ISO400

Also known as Dorid Nudibranch, Nudibranch, Purple-edged Ceratosoma, Three Lobed T-bar Nudibranch, Tribobate Ceratosoma, Trilobatum Sea Slug. Found singly or in pairs amongst sand and rubble areas of coral and rocky reefs. They feed on sponges, growing up to 10cm long, They are widespread Indo-West Pacific, upto 30m depth.

Doto ussi by Marc Broadbent DSC-RX100M4: 1/125, F9, ISO125

Doto ussi feeds exclusively on hydrozoonpolyps, especially on Aglaophenia cupressina. This species could be yellow or bluish-grey. Doto ussi looks like bunch of grapes.