#benthic invertebrates

[uncharismatic-fauna]

Another Day, Another Pacific Sand Dollar

The eccentric sand dollar, aka the sea-cake, biscuit-urchin, western sand dollar, or Pacific sand dollar (Dendraster excentricus), are found in the intertidal zone and near-shore sandy bottoms from Alaska, US to Baja California, Mexico.They are the only sand dollars endemic to the Pacific Northwest, though they share the rest of their range with other species. Live individuals are seen either partially buried upright or lying flat on the ocean floor, depending on the strength of the current. To prevent themselves from being swept away, juveniles will also ingest sand to weigh themselves down. Although they are not social, they can form large colonies with as many as 6 sand dollars in a square m (1 sq yd).

Pacific sand dollars are named for their resemblance to silver dollars, especially the bleached exoskeletons that commonly wash up on beaches. Most adults average about 8 cm (3 in) across, though individuals as big as 10 cm (4 in) have been found. The body is a flat disc coated in small, purple tube-like feet and sensory organelles called cilia. The feet are used both for moving across the ocean floor and for pulling oxygen from the water. The mouth and anus-- a single opening-- are located on the sand dollar’s underside. Inside the mouth are five teeth and jaw plates known as doves; together they form a structure known as Aristotle’s lantern, which is unique to echinoderms like sand dollars and sea stars.

D. excentricus is a suspension feeder, using its feet and cilia to pull food from the water or direct it along special groves on the body’s underside. Their main prey are microscopic larvae, copepods, diatoms, algae, plankton, and detritus. The sea-cake is predated upon by a number of sea stars and fish, as well as crabs and sea gulls. To avoid being eaten, adults bury themselves in the sand and larvae will duplicate themselves via a process known as budding and fission, which creates smaller individuals that can distract potential predators.

Although western sand dollars have seperate sexes, they are broadcast spawners. In late spring or early summer, males and females congregate and release gametes into the water where they become fertilized. Larvae, also known as prisms, hatch just a day later. This larvae floats freely through the water, growing arms and metamorphosing into a echinopluteus larva. Once they reach 8 arms, the larva begins to develop an exoskeleton or echinus, and resembles a small adult. The final stage of growth is triggered by chemical cues released by other adults; after this, individuals become sexually mature and settle on the ocean with other sand dollars. In the wild, adults can live up to 13 years.

Conservation status: Although the IUCN has not evaluated the Pacific sand dollar, they are regularly threatened by ocean acidification, warming, and bottom trawling.

If you like what I do, consider leaving a tip or buying me a ko-fi!

Photos

Chan Siuman

Brian Starzomski

Alison J. Gong

[nereididae]

Being a benthic taxonomist is fun!

[iii-days-grace]

I rarely go into the tags and I hoard a LOT of posts in my drafts as you can see, so just for shits I've been trying to see if I can actually max out my queue (currently the limit is 1000 total and 50 posts a day).

[barstoolblues]

i see tumblr has discovered the sheepshead wrasse

[semiotomatics]

tragic: local nerd absolutely wrecks their neck while looking at bugs in creek bed, more at 11

[oasisofgalaxies]

I’m so scared for tomorrow wtf am I going to do with myself

[vestaignis]

Бисса (лат. Eretmochelys imbricata) — один из редких видов морских черепах, которому грозит полное исчезновение. По внешнему виду ее можно перепутать с зеленой черепахой, от которой бисса отличается только меньшими размерами и весом: взрослая особь имеет длину тела от 60 до 90 см при массе около 45-55 кг. Панцирь биссы сверху коричневый с красивым желто-пятнистым рисунком и имеет сердцевидную форму. Ещё одна особенность внешнего вида - заострённый, похожий на клюв кончик морды.

Второе название биссы — настоящая каретта — означает, что именно эта черепаха дает самые ценные, "настоящие" роговые пластинки, из которых изготавливают различные сувениры: гребни, шкатулки и прочие мелочи. Очень жаль, что любовь человечества ко всяким безделушкам привела вид к такому плачевному состоянию. Впрочем, мясо биссы тоже ценится в некоторых странах. Разумеется, нелегально, так как настоящая карета уже давно внесена в Международную Красную Книгу и находится под охраной различных организаций. При этом гурманов вовсе не пугает тот факт, что деликатес может оказаться ядовитым из-за пищи, которую сама черепаха ела накануне.

Встретить ее можно в Атлантическом и Тихом океанах: ареал настоящей каретты простирается от умеренных вод северного полушария до умеренных вод южного. Вот только гнездится бисса исключительно в тропических широтах. Населяет преимущественно скалистое мелководье, коралловые рифы, лагуны и заливы с мангровыми берегами. Мелкие прибрежные воды, заливы и устья рек с илистым или песчаным дном — обычные места обитания биссы. Она держится чаще в тех местах, где подводной растительности мало. Настоящие каретты всеядны, но отдают предпочтение животной пище- их рацион составляют бентосные беспозвоночные, медузы, анемоны и морские губки, причем только определенных видов, а некоторые из них и вовсе ядовиты для других существ.

Еще один интересный факт этот вид черепах способен светиться в темноте.

The hawksbill turtle (Latin Eretmochelys imbricata) is one of the rare species of sea turtles that is threatened with complete extinction. In appearance, it can be confused with the green turtle, from which the hawksbill differs only in its smaller size and weight: an adult has a body length of 60 to 90 cm with a weight of about 45-55 kg. The hawksbill shell is brown on top with a beautiful yellow-spotted pattern and has a heart-shaped shape. Another feature of its appearance is the pointed, beak-like tip of the muzzle.

The second name of the hawksbill turtle is the real caretta, which means that this particular turtle produces the most valuable, "real" horn plates, from which various souvenirs are made: combs, boxes and other little things. It is a pity that humanity's love for all sorts of trinkets has led the species to such a deplorable state. However, hawksbill meat is also valued in some countries. Of course, illegally, since the real carriage turtle has long been included in the International Red Book and is protected by various organizations. At the same time, gourmets are not at all afraid of the fact that the delicacy may be poisonous due to the food that the turtle itself ate the day before.

You can meet it in the Atlantic and Pacific oceans: the range of the real carriage turtle extends from the temperate waters of the northern hemisphere to the temperate waters of the southern. But the hawksbill nests exclusively in tropical latitudes. It inhabits mainly rocky shallow waters, coral reefs, lagoons and bays with mangrove shores. Shallow coastal waters, bays and river mouths with a muddy or sandy bottom are the usual habitats of the hawksbill. It is more often found in places where there is little underwater vegetation. True carettas are omnivorous, but prefer animal food - their diet consists of benthic invertebrates, jellyfish, anemones and sea sponges, but only of certain species, and some of them are completely poisonous to other creatures.

Another interesting fact is that this species of turtles can glow in the dark.

Источник:://more.fandom.com/ru/wiki/Бисса,/ornella.club/15248-morskaja-cherepaha-bissa.html,/zoo-ekzo.ru/node/6163, //www. zoopicture.ru/bissa/,animals.pibig.info/6018-cherepaha-karetta.html, /ru.pinterest.com/pin/68737846851/.

[life-on-our-planet]

Pegasidae are a family of fishes, also known as seamoths, that use modified pelvic fins to walk slowly along the ocean floor. Males & females form close long-term pair bonds, and couples can usually be seen together feeding on various small benthic invertebrates. ©

[iguanodont]

Illustrations and notes on two small invertebrate animals found along the Twowi coastline.

The first is a soft bodied creature from a diverse family of benthic invertebrates characterized by lack of eyes, echinoderm-like tube feet, and an ability to generate copious amounts of mucus from the dermis. Affectionately referred to as “little shrouded sister” in the local language, this creature is a rare but handsome find in the bottom of deep pools during Twin Moon tides, when the water recedes the furthest. It defends itself from predators with acrid tasting toxins in the mucus coating its “shroud”, which are released within seconds of being attacked. According to local legend, they are born of unfed larvae thrown into the sea, which survived by latching onto the backs of fish.

The second is a shelled animal whose name means “jointed worm”, though another common moniker is the “mud-rattle”. It gets this name from its peculiar shell, which links to each previous molt to form a long, articulated tail reminiscent of a rattlesnake’s. However, this armored tail carries no warning; it is simply an eye-catching distraction. As long as the vital organs in the first segment remain unharmed, this worm can live to grow another tail. They inhabit muddy sea floors across a wide swath of the world’s oceans, and range in size from just 2 cm to more than a meter. Ease of collection and tender flesh make this creature a popular seafood; boiled, steamed, or fried; it is arguably the “shrimp” of birg cuisine. The handsome shells are also commonly re-articulated for a second life as rattles and jewelry.

________

Also available as a print!

Patreon | Kofi

[farcillesbian]

oh you're watching a stream? what's your favourite? mine is the one just outside of town and I like to look out for aquatic insects and watch the way the water moves around the rocks... my favourite streamers are the tadpoles and the benthic invertebrates :)

[todaysbug]

December 12th, 2023

Sea Mouse (Aphrodita aculeata)

Distribution: Found in marine habitats of the northern hemisphere; the North Atlantic, North Sea, Baltic Sea and the Mediterranean Sea.

Habitat: Benthic; lives from the sublittoral zone down to a maximum of 1000 metres.

Diet: Carnivorous; feeds mainly on other invertebrates such as small crabs, hermit crabs, mollusks, nemerteans and other polychaete worms.

Description: Despite its caterpillar-like appearance, the sea mouse is actually a polychaete worm! Its most obvious feature is the dense mat of hairs, or setae, that cover its body. While most are a brownish-red colour, these are intermingled with glassy hairs (especially on either side of its body), which have an iridescent quality. These hairs are usually reddish in colour, but become a bright bluish-green when the light hits them a certain way. This acts as a defence mechanism to ward off predators, acting as a form of aposematism, but also acts as camouflage, with the worms appearing brown from above (blending in with the substrate) and blue from the sides (blending in with the water).

(Images by Gert Oxby and Michel Garnier)

[fishenjoyer1]

Fish of the Day

Today's fish of the day is the reef triggerfish!

The Reef Triggerfish, also known by Hawiian name humuhumunukunukuāpuaʻa, and scientific name Rhinecanthus rectangulus, is known for its prevalence across the indo-pacific, and for being Hawaii's state fish! Their range stretches from the Hawiian islands to the Eastern Philippines,Northern Australia, Indian ocean, small sections of the red sea, and the mediterranean. This fish lives its life out along reefs and other sea shelves, as their hunting style consists mostly of digging in the sand and rocks for prey, similar to pigs digging for truffles. Their diet consists of reef invertebrates, algae, small crabs, sea urchins, and other benthic animals. This diet can support them to sizes of 10-12 inches, which is the smaller range for triggerfishes.

These fish, like many other triggerfish, gain their name from their ability to fire and aim jets of water, which it will also use to hunt and find prey beneath the surface. They also will use this against other fish and larger beings in their territory, as reef triggerfishes are intensely territorial, and solitary other than in breeding season. This can manifest in cases where reef triggerfish chase and bite humans viewing reefs. When met with predators, the reef triggerfish, similar to other triggerfish, finds small holes within rocks or corals that it will lodge itself within. The first dorsal spine will act as a physical barrier that can lock in an upright position, making it harder for predators to pry it out of their safe havens. Due to the shape of their spines and fins, these fish can swim forward, backward, and hover in the water.

Like most fishes, reef triggerfish have a breeding season from April-August, and classically have females lay eggs and males fertilize in groups. This being the one of the only times they interact with other of their species intentionally. Then after this, a female will build a nest, and wait with eggs until a few weeks after they hatch, at which point the fish will set out independently. Reef triggerfish can also change coloration, turning a more vibrant shade for breeding seasons. They will also present vibrantly when healthy, sexually mature, and unthreatened. They can also change colors to better match an environment around them, and do so nightly when they settle into holes to rest.

Have a wonderful day, everyone!

[sharkposting]

Special greek shark!!

I'm in Greece right now so for the next couple days I will only cover sharks that can be found around the Mediterranean sea!

Daily shark day 10:

Angel Shark

Squatina squatina, the angelshark or monkfish, is a species of shark in the family Squatinidae (known generally also as angel sharks), that were once widespread in the coastal waters of the northeastern Atlantic Ocean. Well-adapted for camouflaging itself on the sea floor, the angelshark has a flattened form with enlarged pectoral and pelvic fins, giving it a superficial resemblance to a ray. This species can be identified by its broad and stout body, conical barbels, thornless back (in larger individuals), and grayish or brownish dorsal coloration with a pattern of numerous small light and dark markings (that is more vivid in juveniles). It measures up to 2.4 m (7.9 ft) long. Like other members of its family, the angelshark is a nocturnal ambush predator that buries itself in sediment and waits for passing prey, mostly benthic bony fishes, but also skates and invertebrates. An aplacental viviparous species, females bear litters of seven to 25 pups every other year. The angelshark normally poses little danger to humans, though if provoked, it is quick to bite. Since the mid-20th century, intense commercial fishing across the angelshark's range has decimated its population via bycatch – it is now locally extinct or nearly so across most of its northern range, and the prospects of the remaining fragmented subpopulations are made more precarious by its slow rate of reproduction. As a result, the International Union for Conservation of Nature has assessed this species as Critically Endangered.

[taxonomytournament]

Taxonomy Tournament: Echinoderms

Articulata. This class is made up of sea lilies, which have a stalk an attach themselves to substrate in their adult forms, and feather stars, which are free-moving. They feed using arms with feathery pinnules.

Asteroids. This class is made up of starfish, seabed invertebrates most of which predate on smaller benthic invertebrates. They are capable of regenerating lost limbs.

[herpsandbirds]

Saw some of the jellyfish you posted and wanted to ask what your favourite marine invertebrate/s are (jellyfish or otherwise)?

As a marine biology enjoyer, I like learning about cephalopods, nudibranchs and jellyfish. Plus I think they're very pretty.

But I'll stay well away from the cone snails, the blue-ringed octopus and the venomous jellyfish species. 🤣

Thank for this question!

I am more of a terrestrial biologist, but I absolutely love marine biology. More to the point, I absolutely love marine invertebrates, and it's hard to narrow down which ones are my absolute favorites. 

1.  Cephalopods are one of my favorite groups of animals, and within that I really love the cirrate octopods.

2. Sea Pigs are just really wonderful creatures, and I always include these strange little deep sea benthic holothurians in every list of favorite animals. 

3. The Sea Hares are a group of marine gastropods that I think don't get enough love. One time Paxon and I saw one next to a rock jetty on Galveston Island, and I squealed and almost fell in the water.



[death-mothblog]

Plectorhinchus chaetodonoides, the harlequin sweetlips, clown sweetlips, spotted sweetlips or many-spotted sweetlips, is a species of marine ray-finned fish, a sweetlips belonging to the subfamily Plectorhinchinae, one of two subfamilies in the family Haemulidae, the grunts. It is native to the Indo-Pacific region. This species is of minor importance to local commercial fisheries and can be found in the aquarium trade

Plectorhinchus chaetodonoides has fleshy lips which become moderately swollen as the fish grows, there are 6 pores on the chin but no central pit.< The dorsal fin typically has 12 spines, although rarely it has 11 spines. and 18-20 soft rays, the soft rayed part of the dorsal fin has a height which is roughly equal to the length of its base. The juveniles are brownish with large, discrete creamy white blotches on the body these develop brown spotting as the fish matures. As they grow into adults the coloration slowly develops a greyish background colour broken large, dark brown spots, these spots having a greater diameter of the iris. The maximum recorded total length is 72 cm (28 in), although 60 cm (24 in) is more typical, and the maximum published weight is 7 kg (15 lb). It is thought that the juveniles are Batesian mimics of poisonous flatworms. The caudal fin of juveniles is deeply forked and has wide rounded lobes both of which are mostly white marked with a large brown spot, in adults it is much less forked.

Plectorhinchus chaetodonoides is found in coral-rich parts of clear lagoons and on seaward reefs. The adults are solitary fish, living in the vicinity of and sheltering beneath ledges or caves during the day. The juveniles are found sheltering in corals. It is a carnivorous species which preys on benthic invertebrates such as crustaceans and molluscs, as well as fishes, which it forages for during the night. The juveniles typically swim in a head down posture wildly undulating their fins as they swim, a behaviour which may mimic toxic or distasteful platyhelminths or nudibranchs and so provide some protection from predation.