#freshwater crustaceans

[aquariuminfobureau]

A new crayfish has been described from the tributaries of the Warsamson River, in the Vogelkop Peninsula, of western Papua New Guinea. The 'new' crayfish species has received the name of Cherax warsamsonicus, the Warsamson River crayfish, although it was already known to aquarists and traded, as Cherax 'Irian Jaya', 'Hoa Creek', or 'Pink Coral'. Thus C. warsamsonicus is a good example of how discovery is not the same thing as formal, scientific description. The wild animals can have a total length of up to 11 centimeters, or a little above 4 inches.

Cherax are a genus of crayfishes or freshwater lobsters, that is endemic to the Australasian realm. The closest living relatives of the Australasian crayfishes are inhabitants of Madagascar and South America. Which is to say, a former distribution associated with Gondwana, whereas the other crayfishes are assumed to be a related, Laurasian group. The relationships between crayfish has often been used as evidence for continental drift, and the related biogeographic phenomenon, known as vicariance.

As a genus, Cherax is one of the most speciose genera of crayfishes, and is naturally present on both Australia and New Guinea. On Australia they are most commonly known as the yabbies, although the species called the marron, also belongs to this genus. However is is the New Guinea morphs of Cherax sp. that have more recently captivated the imaginations of aquarists, these morphs appearing in the trade before their formal descriptions.

C. warsamsonicus is described from a shallow, moderately flowing tributary of the Warsamson, though it is reportedly also found in the river itself. The water pH was around 6.5, the temperature was about 25 or 26 degrees centigrade. Reportedly they are also fairly omnivorous foragers, as you might expect of a Cherax species, although I do not have dietary information for this new species in the wild, beyond anecdotes that they are as easy to feed as are the other Cherax species.

Cherax sp. are omnivorous with a largely vegetarian bent, but they obtain animal protein through foraging activities, and not by active predation. Animals such as snails are consumed, and potentially sleeping fishes, but not vigorously motile animals. Other factors can lead to confrontations, when crayfish are housed with benthic fishes or crustaceans that use the living spaces within the aquarium. However in contrast with certain other crayfishes, Cherax sp. are less antisocial with their own kind, assuming that their environment allows each animal sufficient space and retreats.

Plants however, are very likely to be eaten by these herbivores, or if not, they could be uprooted by their ambulatory or burrowing activities. C. warsamsonicus excavate short burrows, but alternatively they hide themselves among rocks and pieces of detritus in the stream. Presumably they feed on vegetable detritus more than living plants in the wild, because there are few of the latter in the tributaries inhabited by C. warsamsonicus.

[uncharismatic-fauna]

Uncharismatic Fact of the Day

What does a unicorn look like? Well for starters, it has six legs, two large claws, is bright purple...wait, no that's just the freshwater purple crab! Originally thought to be just one species, Insulamon unicorn, DNA analysis revealed that populations on other islands were in fact separate species, bringing the total number of Insulamon crabs up to 4.

(Image: One of the new species of Insulamon crab, Insulamon palawanense, by Jolly Ibañez)

If you send me proof that you’ve made a donation to UNRWA or another organization benefiting Palestinians-- including esim donations-- I’ll make art of any animal of your choosing.

[typhlonectes]

Big Sandy Crayfish

The Big Sandy, is a federally threatened species that is only found in the Big Sandy River basin in Virginia, Kentucky and West Virginia. And we have some pretty BIG, Big Sandy news.

For the first time ever, hatchery-reared Big Sandy crayfish have been released back into their native waters! Biologists recently released the first successful cohort — 77 crayfish — at multiple sites throughout Virginia's McClure River. This news is cray!

Photo by Brett Billings/USFWS

[blatentmisinformation]

Lobsters start their life cycle as small shrimp in rivers, becoming crayfish as they mature and migrating to the sea in adulthood.

[lake-lady]

Zooplankton are tiny crustaceans that occupy a variety of roles in Great Lakes food webs, from open water filter feeding to benthic decomposers 🩵

[miyrumiyru]

Mommy crayfish and her baby crayfish <3

Korean Crayfish (Cambaroides similis)

[ouzel-time]

Ragu has been casting spells all day what do I do with him

[theyshapedlikefriends]

Crawfish & Catfish

[theskyisdown]

BEHOLD THE SHRIMP

Got some Neocaridina shrimpies and some nerite snails for my new freshwater tank and OH MY GOD THEYRE SO CUTE

[drhoz]

#2586 - Paranephrops planifrons - Northern Koura

One of Aotearoa's two endemic freshwater crayfish - this one is most common on the North Island, and along the West Coast of South Island. Both Paranephrops are important resources to the indigenous Māori, and surprisingly given the troubles facing every second species I've covered lately, are not considered treatened.

Parastacid crayfish are found only in the Southern Hemisphere, with extant members in South America, Madagascar, Australia, New Zealand, and New Guinea, and extinct taxa in Antarctica - a classic Gondwanan distribution. They're most diverse in Australia.

Hokitika National Kiwi Centre, Aotearoa New Zealand

[aquariuminfobureau]

Most of the shrimp morphs favored by freshwater aquarium hobbyists, are Neocaridina sp. or other fan shrimps. However the South Asian species Macrobrachium agwi is very different. This is the striped 'prawn' or candy shrimp, or the dwarf or bumblebee large-armed shrimp, where 'large armed' is a translation of the genus name Macrobrachium. Before its formal description as a species, M. agwi was identified as a distinctive morph belonging to the genus, and traded as Macrobrachium sp. 'Banded'.

From the tips of their rostrums to the tips of their telsons, M. agwi are around 5 to 6 centimeters or 2 to 2 and a 1/3 inches long. The long claws are not included in this measurement, but they add significantly to the length of the animal, when they are in extended posture. Such a length is much smaller than that of some well known Macrobrachium species, and that is why M. agwi is sometimes traded with the name 'dwarf', although there are other small species among Macrobrachium.

M. agwi is a member of the successful and diverse genus Macrobrachium, to which a large number of species belong. Although it is customary to label Macrobrachium as prawns, many would argue that they are in actuality shrimps, although it is semantic. Also the genus Palaemon, although they are 'the' prawns on the British table, would also technically be shrimp using the same argument. In addition to their use in aquaria, a small number of Macrobrachium sp. are aqua cultured as food, primarily M. rosenbergi. Aquacultural interest in farming members of this genus has increased the knowledge base available for their aquarium care, though the focus is only on the large species that humans culture for food, not M. agwi.

When wild Macrobrachium sp. are exported for the aquarium trade, the exact species involved may be difficult to ascertain. Macrobrachium are mostly freshwater animals as adults, although some species in the genus are estuarine, and only one of these species is also faculatively marine. The planktonic larvae of a number of Macrobrachium species are exported out to sea downstream, therefore they possess tolerance of low salinity, before losing it, and later regaining the tolerance as late juveniles migrating upstream.

Many species of Macrobrachium thus require saltwater for their larval development, however M. agwi has abbreviated or direct development, and completes its entire life cycle in freshwater. M. agwi carries fewer and larger eggs than do some other freshwater Macrobrachium species, budgeting its energy into fewer offspring, with an abbreviated larval life after hatching. These larvae do not feed but continue to be sustained by the yolk donated by their mother. The development of their jointed appendages becomes accelerated, because these freshwater larvae are benthic and non-planktonic from the start.

In freshwater and some other environments, such a life history comes under positive selection, because the amount of plankton available as food for feeding larvae, is either consistently low, or is unpredictable. Such a life history has repeatedly evolved among the clade of shrimps, crabs, and lobsters. M. agwi and other fully 'freshwaterized' shrimp have broken completely with the habitat of their marine ancestors, and have also lost their physiological tolerance of saltwater at any of their life stages, because their ancestors had no further need to continue tolerating saline waters.

The species M. agwi was described from specimens collected at Barobisha, in the Alipurduar District of West Bengal but close to her border with Assam. The climate of Alipurduar is monsoon-influenced and shows variation over the year, from an air temperature of 14 degrees centigrade in the coolest month, to 34 degrees in the warmest month. The water of the Kaljani, the river of Alipurduar, usually has a pH between 7 and 8, sometimes a little higher or lower, but circumneutral and shifted towards baseness.

The water temperature there may vary according to the month, with monthly temperatures as low as 10 and as high as 32 degrees. In neighboring Koch Berar, the main river is the Torsa and the climate is similar to that of Alipurduar. The water temperature of the River Torsa was found to vary from 18 to 29 degrees, and the pH is similar to that of the River Kaljani. There is no major river through Barobisha itself, but the neighboring waters assumedly have comparable parameters. Streams in neighboring western Assam can have a pH of 6.4 to 6.6.

Macrobrachium are regarded as omnivorous benthivores, or generalists feeding on a breadth of plants and animals on the substrate. Although plant material is taken, Macrobrachium show a preference for animal protein. Although their 'arms' are long, their 'claws' are proportionally small, thus limiting the damage these shrimp are capable of in the aquarium. Smaller species of Macrobrachium are often considered safe to cohabit with some fish, although fish eggs and small motile animals such as small fish, will likely be seen as food by these shrimps, and they will certainly consume snails. Juveniles of large Macrobrachium species, can kill and consume snails with a shell diameter almost 3/4 of their own length.

Smaller Macrobrachium species will not kill fish their own size, but the larger species of the genus are reportedly able to. Eggs and fry of fishes, and the larvae of other shrimps, will likely be eaten even by the small species of Macrobrachium. Macrobrachium species appear to vary in their intraspecific competitiveness and tendencies towards cannibalism, but each individual requires a sufficient number of opportunities in the aquascape, in which to choose shelter from cohabiting conspecifics. Therefore, although M. agwi can be housed in small groups of conspecifics, they must not be overcrowded, each animal must be able to avoid confrontation, and also retreat to shed whilst they are growing, without facing competition for these refuges.

In some Macrobrachium species, molting shrimp may be vulnerable to cannibalism, whilst they are still soft. Confrontations in members of this genus, can also result in the loss of whole or partial limbs, or other severe damage. Therefore it is important to avoid these animals stressing one another. Smaller Macrobrachium species do not uproot or otherwise seriously disturb plants in the aquascape, although the larger species in the genus can be destructive, especially to delicate plants. In anecdotes from the tropical aquarium trade, these shrimp are often kept in water with a circumneutral pH, and at an appropriate temperature of 18 to 26 degrees centigrade, befitting their origins close to the Himalayas.

[thedisablednaturalist]

Mr pinchys tank is all set up and he's finally acting more like himself, curiously inspecting the new setup

[musicalsiphonophore]

why are water fleas so fuckemn CUTE

awwwwww look at her colours

and the little diagram?!???

<3 i’m love

they’re not even flea-fleas. they don’t bite. they filter feed. peaceful little buggies

[typhlonectes]

A new freshwater crab species of the genus Vela Bahir & Yeo, 2007 (Decapoda: Brachyura: Gecarcinucidae) from the Western Ghats of Karnataka, India

SAMEER KUMAR PATI, PARASHURAM PRABHU BAJANTRI, GOPALKRISHNA DATTATRAYA HEGDE

Abstract

Vela bandhavya sp. nov., a new species of gecarcinucid crab is described from the Central Western Ghats, Uttara Kannada district, Karnataka state, India. 

The new species can be immediately distinguished from three other species of Vela Bahir & Yeo, 2007, mainly by its short male sternopleonal cavity and a relatively shorter distal article of the male first gonopod. 

The diagnosis of Vela is revised to accommodate the new species, and an illustrated identification key is provided for all four species. An anomalous adult male crab, with a pair of pleopods on the pleonal somite 5 in addition to the male gonopods, is also reported.

Read the paper here:

https://mapress.com/zt/article/view/zootaxa.5239.1.5

[gemfyre]

So my newest obsession is taking samples from waterways/ponds and looking at them under my microscope. I need a compound microscope ASAP, right now I just have a kind of field/stereo microscope, and the images get really crappy when zoomed in.

So anyway, feel free to go to my iNat and ID my shit?

[lake-lady]

The lake had some spot on vibes today (it always does though)