The Complete Life Cycle Of Lobsters (+ Reproduction)
Lobsters’ reproduction is a very interesting and quite long process as it can take about 20 months from mating to hatching. If you ever wondered how lobsters reproduce and what their life cycle looks like, in this blog post, we’ll talk all about that. However, let’s begin with a quick answer:
Lobsters reproduce sexually by male putting a packet of sperm into the female’s sperm pouch where she carries the sperm, fertilizes it with her eggs, and carries the eggs until they hatch. We can divide the life cycle of lobsters into four stages: eggs, larvae, juvenile, and adult stages.
However, this certainly doesn’t tell the whole story. Below, I’ll explain more about how lobsters are born and what their life cycle looks like. Furthermore, I’ll explain when lobsters reach their reproductive maturity, when they reproduce, and how to tell the difference between male and female lobsters. Read on!
How are lobsters born? (Sexual reproduction)
Lobsters reproduce sexually, meaning the process involves both male sperm and female eggs. However, before lobsters mate, there are a few things they do to get prepared. First, the female needs to shed her shell, which is a common process for lobsters called molting.
But, because the female will be in a vulnerable unshelled state, she needs to select the right male to protect her. The male is selected by lobsters’ fights where the winner establishes the social order. The dominant male will mate first.
Next, when the male is ready to show affection, it releases pheromone – a chemical linked to sexual attraction. What is interesting about lobsters is that this chemical is located in lobsters’ urine, so they actually pee on each other. Interestingly, urine is used as the main way of communication between lobsters.
The winning lobster will have urine that smells differently than the losing lobster, smelling more attractive to females. When ready, it shoots urine in the female direction, and if the female likes the smell, it gets closer and approaches the male’s burrow. Next, of course, she will pee on his face as well to show she’s interested and ready to mate.
After the male lets the female move into his burrow, they start stroking each other with antennae and with feet that are covered in taste receptors. This foreplay can last several days, and when the couple it ready, the female sheds her shell.
She slowly removes her old hard shell together with the old pouch where she had banked sperm from a previous mate. Next, the male suspends himself above the female and lifts her gently to face him, cradling her in his legs. He puts a packet of his sperm into her new sperm pouch, using his first pair of abdominal appendages, called gonopods.
The sperm packets are located underside of the female’s body. After the male deposits sperm, the female stores it for up to 15 months before she releases eggs to fertilize them, which I’ll explain more in the life cycle paragraph.
Below you can see the video of the lobsters mating and the female hatching eggs:
After the mating event, the vulnerable female remains safe in the male’s burrow for up to two weeks. During this time, her new shell forms and hardens to protect her from enemies. After that, the female must leave, allowing the next female in the area to mate with the dominant male as well.
During this mating period, the female’s urine sends signals to other females that the male has coupled up. She’ll carry the male’s sperm until she’s ready to release her eggs and fertilize them to start the life cycle of a newborn lobster.
The life cycle of lobsters
After about 9 to 15 months, the female begins to release eggs through openings at the bases of the third pair of walking legs. She does that by cupping her tail and pushing eggs out of her ovaries. She passes them through the seminal receptacle, where they are fertilized with stored sperm.
The number of fertilized eggs depends on the age, size, and species of a female lobster, but it ranges from 100,000 up to 1,000,000 eggs that the female carries under the tail.
Eggs are attached to a female’s walking legs, called pleopods or swimmerets, thanks to a glue-like substance that the female excretes. She carries eggs for another 9-12 months, depending on conditions and species.
We can divide lobsters’ eggs into three stages: early, mid, and late stages. During the early stage, the eggs are greenish in color. Their color is uniform, and they lack eye spots. When eggs enter the mid-stage, they start having two-toned color and black dots, which are eye spots.
They’re also dark green in color, almost grey or purple. During the last stage, eggs take on a brownish to reddish color, and their eyes become large and turquoise in color. When eggs start becoming light blue, that means they’re going to hatch very soon.
Interestingly, the female can’t molt during this time because eggs would be removed together with the shed shell. When the time is right, the eggs begin to hatch. To do that. the female lifts her tail into the current and fans them with her swimmerets.
Since eggs don’t develop at the exact same rate, they don’t all hatch at the same time. Thus, hatching can take several days or even longer, depending on the water temperature. During hatching, the female releases about 700,000 babies, which are called larvae – the next stage of lobsters’ life cycle.
When the eggs hatch, they’d don’t look like their parents yet. They have a flatten shape that allows them to drift and spin in the ocean. Unfortunately, these many free-swimming larvae are like a buffet for many predators. That’s why only less than 3% of the larvae will survive and grow into the adult stage.
Larvae begin their 3 stage journey to become juvenile lobsters. Before it achieves another stage of its life cycle, it spends several weeks in the water column, free-floating and feeding on tiny zooplankton. The larvae will molt about four times – entering a new stage and size with each molt.
The first stage larva is completely transparent, with large dark eyestalks, and about eight millimeters (1/6 of an inch) long. These larvae are usually concentrated at or near the surface of the water at night and, depending on the intensity of sunlight, can be either close to the surface or plunge deeper during the day.
This up and down movement through the water is caused by the larvae’s response to light, which varies during and between each stage so that they are either attracted to or repelled by light. It’s estimated that the depth these larvae live at varies from 15 to 30 m (45 to 90 feet) each day.
The larva moves by beating the outer branches of its appendages, such as legs and maxillipeds. They can also flex their abdomen to swim backward, but these flexions aren’t as efficient as in later stages. The larva isn’t a strong swimmer yet, so it mostly moves with the current.
The second stage larva is about twice as large as the first stage. Depending on the species, it starts developing claws on their first three legs and has more sensory hairs on all appendages. This larva is still transparent and its behavior is very similar to the first stage larva.
The third stage larva is larger, being about one centimeter (half an inch) in length. Its legs are nearly fully formed but still not functional. The eyestalks are longer and more slender, and the mandibles are thicker with more sensory hairs. This larva is still transparent, but it’s less sensitive to light and so lives in the upper waters.
The larvae may take from eleven to about fifty days to molt through the three larval stages and into the metamorphic postlarval stage. The time mostly depends on the water temperature and larvae develop during warmer months. When the larvae are ready for the metamorphosis, they come inshore.
After the metamorphic molt, the postlarva looks like a miniature lobster and is brownish-red in color. They swim by beating the pleopods of the abdomen, and their technique becomes strong enough that they can swim against some currents.
At this stage, they begin to seek shelter at the bottom of the ocean. Scientists assume that the postlarvae dive down repeatedly to the bottom to examine the habitat there. If the area is not suitable, meaning they cannot build a shelter, they return to the surface and are carried away and to try again elsewhere.
The transition from floating in the open sea (being planktonic) to living on the bottom (being benthic) is a very dangerous period in their lifetime. Many predators, such as crabs or bottom-dwelling fish, are quick for a quick meal. Only a small percentage of lobsters can survive this transition.
Once the postlarva molts again and finds the perfect shelter, it begins its juvenile life. During the first year, when the juvenile is still very vulnerable, it preys on small food particles that have been carried by the seawater through its shelter.
When the juvenile lobster meets its energy requirements and grows, it goes out of the shelter on short trips to find food. However, by this time, it’s larger and stronger, so it has a better chance of protecting itself from predators.
The juvenile lobster continues to grow for about 5 to 10 years before reaching adulthood. During this time, the lobster might molt about 20 times.
Once lobsters reach their adult stage, they are about 23 cm (9 in) long and weigh 680 to 910 g (1.5 to 2 lb), but it may vary depending on the region and species. They’re much stronger and larger than in previous stages, so they can protect themselves efficiently from predators.
They still live in their shelters but go on trips to find food much more often. They mostly feed on fish, clams, crabs, mussels, sea urchins, and sometimes even other lobsters. Their biggest predators are big fish species, seals, and humans.
Adult lobsters continue to grow their entire lives, but at a slower rate, molting every 1-2 years. The clawed lobsters will continue growing their claws, so older species have really large claws, and what comes with it fewer predators.
Lobsters’ lifespan is very long, and they can live to be even over 100 years old.
When do lobsters reach their reproductive maturity?
Male lobsters must reach two aspects of maturity to reach reproductive maturity: physiological and functional. Physiological is reached when a male can produce mature spermatozoa – male sex cells that carry its genetic material. The functional aspect is achieved when the male is capable of mating with a female, meaning the size of their body as well as appendages needs to be big enough.
Females’ sexual maturity also depends on the size of the animal and the capability of extruding eggs. When the female is capable of reproduction, the ovary stages are observed that differ in color, so we can tell in what ovary stage the female is. For instance, during stage one, when the female is immature the ovary is white in color.
During stage 2, it becomes green, and it means that she’s maturing. When the female is fully mature, it becomes green and expands down into the abdomen. During stage 4, when the female is carrying eggs we can observe the white color. During stage 5, white – an ovigerous female carries brown eggs, and during stage 6, she releases white eggs and brown filaments.
When do lobsters reproduce?
The frequency of the lobsters’ annual reproductive cycle mostly depends on the species. For instance, the American and European lobsters typically require two years to produce a single brood, while spiny lobsters can produce three or four broods in a single year.
Lobsters’ reproduction is usually a seasonal event, and it’s mostly related to the water temperature. Typically females extrude eggs in the summer and then hatch them the following summer, after carrying them for 9-12 months.
For instance, the researchers studied the reproductive biology of female Norway lobster throughout an annual cycle from January to December in Greece. They proved a clear seasonality in terms of ovarian maturation and brooding period.
The brooding period peaked in November and December, while the release of eggs from females occurred from January to March. The reason for this can be that in the Mediterranean, in the winter, water temperature and planktonic food availability are at a minimum, so the larva would have a very hard time surviving.
Spiny lobsters, however, spawn from March through August and hatch their eggs within 2-5 months after spawning. They spawn at least annually, but some can do it 4 times a year.
How to tell the difference between a male and female lobster?
There are two main differences between lobsters’ sexes: the shape of the tail and their legs. The male lobster has a very straight tail, while the female’s tail is wider with a slight curve. When it comes to their legs (pleopods), the ﬁrst pair of pleopods are larger and harder in males than in females.
- Mente, Eleni & Karapanagiotidis, Ioannis & Logothetis, Panagiotis & D, Vafidis & Malandrakis, Emmanouil & Neofitou, Nikos & Exadactylos, Athanasios & Stratakos, Alexandros. (2009). The reproductive cycle of Norway lobster. Journal of Zoology. 278. 324 – 332. 10.1111/j.1469-7998.2009.00579.x.
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