Red mangrove crabs
| Red mangrove crabs | ||||||||||||
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Red mangrove crab ( Pseudosesarma moeschi ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Pseudosarma | ||||||||||||
| Serène & Soh , 1970 |
The genus Pseudosesarma , commonly referred to as red mangrove crabs , originally comes from the mangrove forests of Thailand and Southeast Asia. For several years it has also been offered in pet shops in Germany.
Description and system
There are four different types that differ from one another. In all species the males have a pointed abdominal flap (pleon), females a broad one.
- Red mangrove crabs ( Pseudosesarma moeschi, synonym Sesarma bidens ) have characteristic red-colored claws . The color spectrum of the scissor tips is variable from white to cream to yellow. A bulge can be seen on the males' claws. During the readiness to mate, the insides of the legs and the gill regions can also be colored red or orange. The carapace is usually brown, more rarely also speckled. The width of the carapace can be up to 3 centimeters.
- Pseudosesarma edwardsii have a less pronounced scissors bulge, and rounder, more pointed scissors. The face area is flatter overall.
- Red-brown mangrove crabs ( Pseudosesarma crassimanum ) have the same basic characteristics as P. moeschi , but here the claws are orange to dark red, the body and legs olive green with brown and orange parts. In addition, the males do not have a scissor bulge.
- Blue mangrove crabs ( Pseudosesarma bocourti ) reach a maximum carapace width of 4.5 centimeters. Therefore, when fully grown, they can only be kept together in large tanks with the other species mentioned above. Her legs and body are black or blue, the scissors deep blue or black, the tip of the scissors bright red.
attitude
Basics
The keeping of P. moeschi , P. crassimanum and P. edwardsii is generally possible from a tank volume of 54 liters. The P. bocourti should have at least 112 liters is available because of their size. The first three species can be kept together without any problems, P. bocourti should only be kept together with the other species if the tank has a volume of at least 160 liters. Keeping them in brackish water is possible.
Pool equipment
Since these animals live in burrows in their natural habitat, they also need a piece of land in the artificial habitat. Unpolluted soil should be used as the substrate; potting soil available in shops can contain pollutants and poison the animals. As an alternative, mixtures of earth and sand or terrarium humus can be used. Cork tubes as hiding places and stones should be available. A third of land and two thirds of water are ideal for dividing up, with 50% land and 50% water making sense in larger pools. In the water part, gravel and sand are recommended as substrates. There should be enough hiding places for all crabs so that they can delimit their territories and stress is avoided. Mangrove wood roots are an important nutritional supplement. Planting is a problem because the crabs see them as food. Aquatic plants of the genus Echinodorus (sword plants) and Anubias (spear leaves) prove to be useful. Mangrove crabs need a powerful filter that can suck in any droppings and soil, and a constant temperature of 22–26 ° Celsius. The air humidity on the land part should ideally be 90–95%. Mangrove crabs are endowed with excellent climbing skills, so a cover is imperative. One cable is enough for a successful escape.
Diet and feeding
Mangrove crabs feed mainly on fallen leaves in their natural habitat , but are nonetheless omnivorous . Therefore, there should always be leaves in the holding tank. Oak , beech , maple and sea almond leaves are just as much a part of it as alder cones . As already mentioned in the previous text, mangrove wood roots should be laid out in the tank as a nutritional supplement, and they should also be fed with crustacean food from time to time. Mosquito larvae, normal fish food, spirulina algae flakes, fruit and vegetables can also be added as a variety. Care should be taken to ensure that neither copper nor harmful substances are on the feed.
behavior
Mangrove crabs show very pronounced social behavior. Therefore, at least three animals should live together in one housing facility. Males look for their fixed territories, which they defend against any intruder, especially when they are ready to mate. The hiding places must be available in sufficient numbers. New animals in particular tend to be ready to flee, while those who have settled in get used to human society and lose their shyness and leave their territory. There is particular activity in the evening, while the animals stay in their hiding places in the morning and at noon. When males meet, disputes and limb losses can occur (→ molting), also when they meet at the feeding place. Mangrove crabs can develop their own character and recognize their owner. Occasional animals can also be fed by hand and try to climb the keeper.
Socialization
Whether a socialization is successful depends to a large extent on the pool equipment, the pool size and the character of the animals. In order to be able to accept losses, guppies and reproductive dwarf shrimp of the genus Neocaridina make sense.
Molting
As with all decapods, the shell does not grow with you. Therefore, the crabs have at certain intervals skin . Their abdomen bursts open and they get out at the back. Loss of limbs is compensated for when molting, scissors usually need a few moltings before they have reached their full size again. The number of moults decreases with advancing age, a two-year-old moult only two to three times a year. After the molt, the new, soft shell unfolds until it hardens completely after two days. During the growth phase the crab is not protected against attacks and violent impacts. In addition, the color of the crab changes greatly after molting and returns to normal over time.
Diseases and problems
Since the keeping of mangrove crabs in an aquaterrarium requires a lot of specialist knowledge, newcomers often face problems.
- Lime deficiency: Lime deficiency leads to sloughing, which affects the animals or lets them perish. The best prevention is to add a sepia bowl . Soft, lime-free water extracts the mineral from the animal's shell and makes it easier to attack.
- Rust spot disease, burn spot disease: The symptoms are crater-like spots all over the body. Alder cones and sea almond leaves can help heal.
- Social pressure: If too many crabs are kept in too small a space, it is possible that one or more of them will lose their place in the social structure. If they cannot find a place to hide, it is possible that they will either be mangled by the fittest or die as a result of a secondary infection . Such an animal can be recognized at an early stage by severe limb loss. An enlargement of the living space or a restructuring seems to make sense here. For direct treatment, the damaged animal is given a quarantine tank and is additionally treated with alder cones and sea almond leaves.
- Other diseases: Quarantine is recommended for treating almost any disease to prevent it from spreading.
Multiplication
Propagation in nature
Mangrove crabs need salt water to reproduce. The heavily pregnant females release their larvae in brackish water . The larvae then migrate into the open sea, where they pass through several Zoea stages and the Megalopa stage until they return to their home as fully developed young crabs. This type of reproduction is also known as the primitive reproduction type.
Propagation in the holding tank
About every three to four weeks (depending on the temperature) the females can release an egg packet. This contains several thousand eggs. When the package turns gray, the female is separated into a brackish tank. A rearing tank with a volume of at least 54 liters should be run in beforehand. Here, simple sand is sufficient as a substrate, the water temperature should be 25 ° Celsius and the salt content should be 25 grams / liter. Ideally, the pool is ventilated with a simple diaphragm pump . After hatching, the larvae can survive for a maximum of 30 minutes in fresh water, and for several days in brackish water, depending on the salt content. They are fed with spirulina powder, and later also with Artemia . After about four weeks, the first young crabs can be observed, whose carapace width is initially only a few millimeters. In the following weeks you can slowly accustom the young to fresh water.