Portia Labiata - Reproduction and Lifecycle

Reproduction and Lifecycle

Before courtship, a male Portia spins a small web between boughs or twigs, and he hangs under that and ejaculates on to it. He then soaks the semen into reservoirs on his pedipalps, which are larger than those of females.

Females of many spider species, including P. labiata, emit volatile pheromones into the air, and these generally attract males from a distance. The silk draglines of female jumping spiders also contain pheromones, which stimulate males to court females and may give information about each female's status, for example whether the female is juvenile, subadult or mature. Pheromones may help to find jumping spiders' nests, which are usually hidden under rocks or in rolled leaves, making them difficult to be seen.

Portias sometimes use "propulsive displays", with which a member threatens a rival of the same species and sex, and unreceptive females also threaten males in this way. A propulsive display is a series of sudden, quick movements including striking, charging, ramming and leaps.

A laboratory test showed how males of P. labiata minimise the risk of meeting each other, by recognising fresh pieces with blotting paper, some containing their own silk draglines and some containing another male's. Males also were attracted by fresh blotting paper containing females' draglines, while females do not response to fresh blotting paper containing males' draglines. This suggested that the males usually search for females, rather than vice versa. Neither sex responded to one week-old blotting paper, irrespective of whether it contained males' or females' draglines. A similar series of tests showed that P. fimbriata from Queensland showed the same patterns of responses between the sexes.

Among P. labiata and some other Portias, when adults of the same species but opposite sexes recognise each other, they display at 10 to 30 centimetres. Males usually wait for 2 to 15 minutes before starting a display, but sometimes a female starts a display first.

A female P. labiata that sees a male may approach slowly or wait. The male then walks with erect and displaying by waving his legs and palps. If the female does not run away, she gives a propulsive display first. If the male stands his ground and she does not ran away or repeat the propulsive display, he approaches and, if she is mature, they copulate. If the female is sub-adult (one moult from maturity), a male may cohabit in the female's capture web. Portias usually mate on a web or on a dragline made by the female. P. labiata typically copulates for about 100 seconds, while other genera can take several minutes or even several hours.

Females of P. labiata and P. schultzi try to kill and eat their mates during or after copulation, by twisting and lunging. The males wait until the females have hunched their legs, making this attack less likely. Males also try to abseil from a silk thread to approach from above, but females may manoeuvre to get the higher position. If the female moves at all, the male leaps and runs away.

Before being mature enough to mate, females of P. labiata and also P. schultzi mimic adult females to attract males as prey.

P. labiata females are extremely aggressive to other females, trying to invade and take over each other's webs, which often results in cannibalism. A laboratory test showed how they minimise the risk of meeting each other, by recognising pieces with blotting paper containing their own silk draglines and pieces contain other P. labiata females' draglines. If obstacles make it impossible to see whether the other is physically present, she avoids blotting paper containing the other's draglines, but moves with no constraint if she can see that the other female is not around. Draglines seem to act as territory marks, much as many mammals identify conspecifics by scent marking. P. labiata females also avoid rival females of higher fighting ability and spend more time around less powerful fighters. A laboratory test collected samples of the draglines of equal-sized females and then pitted some of them in contests. Other females avoided the draglines of the victors, and spent the majority of their time on draglines of the losers. Similar tests showed that females of P. fimbriata from Australia and P. schultzi from Kenya do not avoid draglines of a powerful fighter.

In P. labiata and in some other species, contests between males usually last only 5 to 10 seconds, and only their legs make contact. Contests between Portia females are violent and embraces in P. labiata typically take 20 to 60 seconds. These occasionally include grappling that sometimes breaks a leg, but more usually one female lunges at the other. Sometimes one knocks the other on her back and the other may be killed and eaten if she does not right herself quickly and run way. If the loser has a nest, the winner takes over and eats any eggs there.

When hunting, mature females of P. labiata, P. africana, P. fimbriata and P. schultzi emit olfactory signals that reduce the risk that any other females, males or juveniles of the same species may contend for the same prey. The effect inhibits aggressive mimicry against a prey spider even if the prey spider is visible, and also if the prey is inhabiting any part of a web. If a female of one of these Portias smells a male of the same species, the female stimulates the males to court. These Portia species do not show this behaviour when they receive olfactory signals from members of other Portia species.

P. labiata usually lays eggs on dead, brown leaves about 20 millimetres long, suspended near the top of its capture web, and then cover the eggs with a sheet of silk. If there is no dead leaf available, the female will make a small horizontal silk platform in the capture web, lay the eggs on it, and then cover the eggs.

Portia females have never been seen eating their own eggs, but in nature females with eggs of their own have been seen eating eggs of other females of the same species. In a test, P. labiata females did not eat their eggs if the testers put them in other female's nests, showing that the test females could identify their own eggs, possibly by chemical means. When the test females and their eggs were restored to their own nests and other females' eggs were also placed in the same nest, the test females ate neither their own eggs nor the "foreign" ones. In nature a female is unlikely to find foreign eggs in her nest, and it might be safest for females to avoid any eggs in their own nests.

For moulting, all Portias spin a horizontal web whose diameter is about twice the spider's body length and is suspended only 1 to 4 millimetres below a leaf. The spider lies head down, and often slides down 20 to 30 millimetres during moulting. Portias spin a similar temporary web for resting.