Malili Lake System

March 6, 2012

The Malili lake system consists of five interconnected lakes drained by the Larona River towards the west into Bone Bay. These five lakes are:

  • Lake Matano
  • Lake Mahalona
  • Lake Towuti
  • Lake Lontoa
  • Lake Masapi

Lake Matano (the northernmost lake) is connected by the Petea River to Lake Mahalona, which in turn is connected to Lake Towuti by the Tominanga River. Lontoa and Masapi are considered satellite lakes as they are not directly connected to the three major lakes, but are part of the Malili system nonetheless.

The image below illustrates this information.


There is great range in the surface area and depths of these lakes, and some variance in their water chemistry.

Lake Matano (Indonesian: Danau Matano)

As mentioned, Lake Matano is the northernmost lake of the Malili lake system. It has a maximum depth of 590m, making it the tenth deepest lake in the world. At 164.1km², its surface area is less than that of Lake Towuti, however.

The water parameters in the shallows of Lake Matano are as follows:

Temperature (°C) 28.7
pH 8.5
General hardness (°GH) 7
Carbonate hardness (°KH) 5
Conductance (μS) 175
Total dissolved solids (ppm) 87.5
Oxygen (mg/l) 6.93

The following shrimp species can be found within the lake:

  • Caridina dennerli
  • Caridina holthuisi
  • Caridina lanceolata
  • Caridina loehae
  • Caridina mahalona
  • Caridina masapi
  • Caridina parvula

Petea River

The Petea River connects Lake Matano to Lake Mahalona. Shrimp that are found within the river are not thus considered riverine, as it is considered an extension of either lake rather than a true river.

The following shrimp species can be found within the river:

  • Caridina holthuisi
  • Caridina lanceolata
  • Caridina loehae
  • Caridina masapi
  • Caridina parvula

Lake Mahalona (Indonesian: Danau Mahalona)

Lake Mahalona is south-east of Lake Matano and north of Lake Towuti. It is far smaller than the two, with a meximum depth of 73m. This lake is connected to Lake Matano and Lake Towuti by the Petea River and Tominanga River respectively.

The following shrimp species can be found within the lake:

  • Caridina holthuisi
  • Caridina lanceolata
  • Caridina lingkonae
  • Caridina masapi
  • Caridina striata
  • Caridina tenuirostris

Tominanga River

The Tominanga River connects Lake Mahalona to Lake Towuti. Shrimp that are found within the river are not thus considered riverine, as it is considered an extension of either lake rather than a true river.

The following shrimp species can be found within the river:

  • Caridina lanceolata
  • Caridina masapi
  • Caridina parvula
  • Caridina tenuirostris

Lake Towuti (Indonesian: Danau Touti)

With a maximum depth of 203m, Lake Towuti is dramatically shallower than Lake Matano. Despite this, Lake Towuti has the greatest volume of all the Malili lakes. This is due to its large surface area of 561.1km².

The water parameters in the shallows of Lake Towuti are as follows:

Temperature (°C) 29.2
pH 8.4
General hardness (°GH) 6
Carbonate hardness (°KH) 4
Conductance (μS) 146
Total dissolved solids (ppm) 73
Oxygen (mg/l) 7.15

The following shrimp species can be found within the lake:

  • Caridina glaubrechti
  • Caridina holthuisi
  • Caridina lanceolata
  • Caridina lingkonae
  • Caridina loehae
  • Caridina masapi
  • Caridina parvula
  • Caridina profundicola
  • Caridina spinata
  • Caridina spongicola
  • Caridina striata
  • Caridina tenuirostris
  • Caridina woltereckae

Larona River

The Larona River is to the west of Lake Towuti and drains the Malili lake system via Towuti Outlet Bay. Shrimp that are found within the river are not necessarily thus considered riverine, as it may considered an extension of Lake Towuti.

The following shrimp species can be found within the river:

  • Caridina lanceolata
  • Caridina masapi
  • Caridina tenuirostris

Lake Lontoa (Indonesian: Danau Lontoa)

Lake Lontoa is a satellite lake within the Malili lake system, and has a maximum depth of 2-4m.

The following shrimp species can be found within the lake:

  • Caridina masapi

Lake Masapi (Indonesian: Danau Masapi)

Lake Masapi is a satellite lake within the Malili lake system, and has a maximum depth of 2-4m.

The following shrimp species can be found within the lake:

  • Caridina masapi

General rivers, not considered extensions of lakes

These are the rivers that are not considered extensions of the lakes within the Malili lake system, and shrimp found within them are considered riverine.

The following shrimp species can be found within the rivers:

  • Caridina mahalona
  • Caridina masapi

Sources:

von Rintelen, K. & Cai, Y., (2009). Radiation of endemic species flocks in ancient lakes: systematic revision of the freshwater shrimp Caridina H. Milne Edwards, 1837 (Crustacea: Decapoda: Atyidae) from the ancient lakes Of Sulawesi, Indonesia, with the description of eight new species.Raffles Bulletin of Zoology57(2).

Logemann, F. and Logemann, C.. “http://blog.garnelenhaus.de”


Exoskeleton

March 4, 2012

A defining feature of the arthropods is their non-living external skeleton (exoskeleton / cuticle) that still allows for growth (albeit noncontinuous) and mobility. The exoskeleton serves a number of functions. Where it is hardened it provides protection and strength, and gives support to the soft tissue, acting as a site for muscle attachment. The cuticle also acts as a physical barrier to pathogens.

Biochemistry of the Crustacean exoskeleton

The crustacean exoskeleton is secreted by the immediately underlying epidermis- a single layer of cuboidal epithelial cells- and so it follows that there is exoskeleton above every epidermal layer. This includes invaginations of the ectoderm and internal structures derived from embryonic invaginations, such as the foregut and hindgut (often referred to as the endoskeleton).

The cuticle is largely composed of protein and α-chitin, covalently bonded to form polysaccharides of N-actylglucosamine monomeric units. It is important to understand that the physical properties of the cuticle can be dramatically altered by chemical processes. Whilst the cuticle is initially soft and flexible, these processes can be used to harden and strengthen it. The two processes relevant to crustacea are sclerotisation and mineralisation.

Sclerotisation is present in all arthropods and is commonly referred to as ‘tanning’, which is derived from how the process darkens the cuticle as a side effect. This process is simply the formation of covalent bond cross-links between protein molecules, which dramatically increases the overall strength and rigidity of the cuticle.

Mineralisation is another method by which arthropods strengthen their exoskeleton, but it is generally only exploited by crustacea and diplopods (millipedes). It is achieved by impregnating the cuticle with calcium salts, usually calcium carbonate.

Structure and composition of the Crustacean exoskeleton

The cuticle has two distinct layers; the epicuticle and the procuticle. The epicuticle is the thin outermost layer. The procuticle is much thicker and can be further divided into two sub-layers, the endocuticle and the exocuticle.
The epicuticle is a thin layer of protein, lipoprotein, and lipid; always lacking chitin. It often has a waxy layer that protects the organism from osmotic influxes- a notable hazard of living in freshwater. The gills (and other similar interfaces) have a much thinner epicuticle with no wax layer, increasing the permeability to gases and ammonia, allowing easy exchange with the environment.

The procuticle is much thicker than the epicuticle, and is generally composed of protein and α-chitin covalently bonded to each other to form complex glycoprotein. This major layer of the exoskeleton is the main contributor to the overall strength and rigidity, and can be further divided into two sublayers; the exocuticle and the endocuticle. The exocuticle is directly beneath the procuticle and may be hardened in areas by sclerotisation. The endocuticle differs in that it is thicker, has less protein, more chitin, and is often strengthened by mineralisation.

Moulting information coming soon…

Sources:

Ruppert E. E., Fox R. S., Barnes R. D., (2004). Invertebrate Zoology, seventh edition. Brookes/Cole, Thomson Learning.

Brusca R. C., Brusca G. J., (2003). Invertebrates, second edition. Sinauer Associates, Inc.

(2008). Encyclopaedia Britannica. Z-Systems, Inc.


Sulawesi shrimp

February 25, 2012

Photographs by Chris Lukhaup. Corresponding shrimp profiles in the sidebar!


The Sun-stripe Shrimp

February 25, 2012

Scientific name:

Caridina profundicola¹

Official common name: (accepted by ESA)

Sun-Stripe shrimp

Unofficial synonyms:

Etymology:

The species name profundicola (“inhabits the depths”) is derived from Latin profundus, which means ‘depths’, and collere, which means ‘to inhabit’. The name refers to how the species occurs at greater depths than other Caridina spp in the lakes.

Origin:

C. profundicola is a lacustrine species endemic to Lake Towuti, Sulawesi, Indonesia.¹

The image below show the distribution of the species within the lake.¹

Habitat:

C. profundicola is found on hard substrate, the majority between large rocks. Mature specimens were found exclusively below 3m depths, whereas juveniles can also be found amongst leaf-litter in shallow water.¹

Size:

Appearance:

The body and appendages of C. profundicola are yellow-transparent and sometimes slightly red. The abdomen bears two conspicuous yellow transversal stripes, which are also distinctive in juveniles. The eggs of this species are a striking green, and very conspicious.

Behaviour:

C. profundicola is a relatively inactive species and will remain still even when disturbed, but will flee rapidly with Caridoid escape reaction if necessary.

Difficulty:

Due to the delicate nature of these shrimp, I recommend only experienced and skilled aquarists attempt to keep this species.

Feeding:

Sexing:

Reproduction:

Reproduction takes place entirely in freshwater, and offspring immediately assume a benthic lifestyle.

Notes:

Sources

  1. von Rintelen, K. & Cai, Y., (2009). Radiation of endemic species flocks in ancient lakes: systematic revision of the freshwater shrimp Caridina H. Milne Edwards, 1837 (Crustacea: Decapoda: Atyidae) from the ancient lakes Of Sulawesi, Indonesia, with the description of eight new species. Raffles Bulletin of Zoology, 57(2).

Images

Chris Lukhaup

“equator.web.fc2.com”:


The Red Orchid shrimp

February 22, 2012

Scientific name:

Caridina glaubrechti¹

Official common name: (accepted by ESA)

Red Orchid shrimp

Unofficial synonyms:

Brown Camo shrimp

Etymology:

The species name glaubrechti is a dedication to Mattias Glaubrecht, “who initiated the current research on endemic species flocks from the ancient lakes of Sulawesi, and who also collected several shrimp specimens”.¹

Origin:

C. glaubrechti is a lacustrine species endemic to Lake Towuti, Sulawesi, Indonesia. It is found mainly in the western part of the lake.¹

The image below show the distribution of the species within the lake.¹

Habitat:

C. glaubrechti is found on hard substrate (rocks and wood), specifically preferring smaller rocks in shallow water. It is still found at depths greater than 3m and on larger rocks, however.¹

Size:

(20 – 25mm)

Appearance:

C. glaubrechti is primarily brown, with several white bands and patches all over the body, including the pereiopods and uropods. The body colour ranges from red to brown, and becomes less intense when the shrimp is stressed. The carapace is slim and terminates with an elongated, slender rostrum that curves upwards. The tailfan bears a white spot on each endopod and exopod.

Behaviour:

Difficulty:

Due to the delicate nature of these shrimp, I recommend only experienced and skilled aquarists attempt to keep this species.

Feeding:

Sexing:

Reproduction:

Notes:

Sources

  1. von Rintelen, K. & Cai, Y., (2009). Radiation of endemic species flocks in ancient lakes: systematic revision of the freshwater shrimp Caridina H. Milne Edwards, 1837 (Crustacea: Decapoda: Atyidae) from the ancient lakes Of Sulawesi, Indonesia, with the description of eight new species. Raffles Bulletin of Zoology, 57(2): 428 – 432

Images

Chris Lukhaup

“equator.web.fc2.com”:


Exoskeleton and moulting

December 18, 2011

Arthropods have evolved a hard, rigid external skeleton (exoskeleton/cuticle) that protects and gives support to the organism’s soft tissue and acts as a site for muscle attachment. The crustacean exoskeleton has two distinct layers; the procuticle and epicuticle. The epicuticle is the thin outermost layer, containing protein and lacking the polysaccharide chitin. The procuticle is much thicker and can be further divided into two sub-layers, the endocuticle and the exocuticle. Cross-bonding of chitin-protein chains in the exocuticle greatly contributes to the overall strength of the exoskeleton, as well as the impregnation of the procuticle with calcium salts such as calcium carbonate.

The obvious problem with having a hard, rigid outer skeleton is that it can not grow with the rest of the body. Arthropods have resolved this problem through moulting of the exoskeleton and growing whilst the new exoskeleton is still malleable. The cycle of moulting is regulated by hormones, and consists of 4 stages:

Proecdysis

The events that occur during this stage are collectively termed apolysis.

The epidermis separates from the procuticle by secreting enzymes that begin to digest the endocuticle. As the endocuticle is broken down, the produced calcium and other solutes are reabsorbed into the blood. The epidermal cells begin to form a new epicuticle.

Ecdysis

Following apolysis, the shrimp is still encased in the old cuticle. When in this state the shrimp is described as being pharate. The shrimp flexes its abdomen to put strain on the old cuticle. This causes it to split between the carapace and the first abdominal segment, allowing the shrimp to spring out or pull itself free. The discarded cuticle is termed the exuvia. An influx of water then causes the shrimp’s body to expand and the new cuticle to stretch.

Metecdysis

After undergoing ecdysis the new, soft cuticle is exposed, so the shrimp is vulnerable and described as being teneral. It is during this time that the shrimp rapidly grows as the cuticle can still stretch. After a few hours the exocuticle will have formed its cross-bonds of chitin-proteins and the procuticle will have fullied calcified, hardening the cuticle.

Intermoult

This is the stage between moults where the cuticle is in its normal state.

Caridina shrimp tend to shed their exoskeletons between every one to two months in maturity, but far more frequently as growing juveniles (especially when the life cycle involved metamorphosis). Adult shrimp that will no longer grow benefit from moulting in different ways. For example, moulting regenerates lost limbs and damaged cuticles, and gives a clean surface for brooding of eggs.

Sources:

Ruppert E. E., Fox R. S., Barnes R. D., (2004). Invertebrate Zoology. Chapter 19, pg 649. Brookes/Cole, Thomson Learning.

(2008). Encyclopaedia Britannica. Z-Systems, Inc.


White-Legged Cardinal shrimp strain

December 7, 2011

Everyone who is familiar with the shrimp hobby will recognise this shrimp – the freshwater Cardinal shrimp, Caridina dennerli. In fact it is often considered the ‘face’ of Sulawesi in terms of aquatics.

Its usual body colouration is opaque red (changing tone from bright red to almost black) with evenly distributed white spots and two pairs of white chelipeds at the front of the body (left). It appears that mutation is relatively common in this species, however; resulting in new phenotypes arising in populations.

Some of you may remember when Chris Lukhaup, renowned freshwater-crustacean photographer, presented images of an unusual Cardinal mutation (right) a while back. This shrimp had less uniform white spots, of varying size and odd distribution. To my knowledge, no attempt has been made to stabilise this mutation in a population.

However, a shrimp enthusiast has bred a new strain of Cardinal shrimp: the White Legged Cardinal shrimp. In this mutation, all pereopods and even the third maxillipeds are white for 3 segments dactyl-up. Stefan Bischoff, breeder of this strain, says he has bred the Cardinal shrimp for 3 years and this new strain for a year. He claims this mutation is stable in his population, and photos seem to confirm this. I would like to point out that according to Stefan the shrimp do not have unusual spot distribution, it is merely camera blur. However, the white colour of the spots seems very strong, so congratulate him on very happy shrimp!

Perhaps the Cardinal will be the new Bee shrimp, forming many mutations in the future and becoming an obsession of the hobby. I feel this shrimp is still given a wide berth due to how difficult it is to keep in aquaria, but perhaps with the new methods for keeping Sulawesi shrimp will come a new breed of aquarist who selectively breed Sulawesi species.

Second photograph courtesy of Chris Lukhaup.

Photographs of White Legged Cardinal shrimp courtesy of Stefan Bischoff.


%d bloggers like this: