Love has more than one name – relations from the animal world
Love is a strong bond that binds loved ones together – it is associated with a sense of understanding, closeness and security. We celebrate it on February 14 – Valentine’s Day, which is the celebration of love. However, is this feeling reserved only for humans? What does a love situation look like in the animal world? We asked our biologists about this.
We will look at the basis of each relationship, i.e. what the choice of a partner looks like. For us humans, this aspect can be complex. Some pay attention to physical features – hair color, eye color, musculature – others to aspects related to the financial situation. So we should not be surprised that it is similar in the animal world but it depends on the species.
Attractive, but also resourceful
For peacocks, the majestic tail is an attribute that makes males attractive. Females, with less fanciful feathers so that they can blend better into its environment, choose partners with the most colorful and impressive tail. This is not only due to the sense of aesthetics, because such tail is a clear indicator of individual quality. If the male has “good genes”, he has no problem with getting food and territory, and his impressive tail lets others know about it. In addition, it is worth remembering that the large colorful attribute of peacock masculinity may also cause difficulty in avoiding predators. So if a male with an impressive tail is able to survive in the environment, he proves that he can effectively take care of himself – and such traits are desirable to pass on to his offspring.
Literal consumption of the relationship in anglerfish
Among animals, we can also find species in which the principle of “opposites attract” is extremely visible. In the genus of anglerfish, i.e. well-known deep-sea fish, characterized by a not very friendly appearance, we can see that males and females are complete opposites. Females are the widely known “monsters of the deep”, while the appearance of males remained a mystery for many decades. It turned out that representatives of both sexes differ from each other so significantly that, based on the features of their external appearance, they can be mistakenly considered separate species. The bodies of males are many times smaller than those of females, and developmentally they resemble young, not fully developed fish. In addition, males are completely blind, and they locate their future partner thanks to the pheromones she secretes, i.e. chemical substances used to attract a partner. Once they meet, they proceed to “consummate” their relationship in a literal way – the male bites into the female’s body, becoming an integral part of her and sharing all his internal systems with her. Such a relationship is established for the whole life, or at least for the whole life of the male.
Female of the genus Anglerfish, photo: Museum of Comparative Zoology/Harvard University
Colorful love dizziness in the black-spotted lizard
There are also species among which females have the opportunity to choose between males, which differ significantly from each other. In the black-spotted lizard, we observe three types of males, which differ in the color of the dewlap. The way males compete resembles a game of rock-paper-scissors. Red-throated males are characterized by having large territories to which they invite many females. However, when the territory is large and there are many partners in it, it turns out to be a challenge to defend them effectively. In this situation, males find themselves with a yellow throat – characterized by a lack of territories and a lack of permanent partners. They take advantage of the opportunity when a male with a large territory is not able to keep an eye on his numerous partners and copulate with them, thus passing on their genes. However, there is also a group of males who protect themselves against such “stealing of females”. They are blue-throated males who have a small territory and only one partner, whom they guard carefully.
Complicated relationships in ruff leks
A similar system has been noticed in ruffs, in which we also find three types of males. First of all, the individuals with large ruffs we know are a class of independent or dominant males – owners of a territory to which they invite many partners. To secure their interests, they recruit satellite males to help them – they do not have their own territories. Such helpers only in the absence of their “boss” start copulation with females. However, the third one deserves special attention, the males, which are confusingly similar to females. Called faeders, not only in appearance, but also in behavior, they resemble females, sometimes copulating with other males. By this trick, they are able to put the owners of the territories and their helpers off guard, and copulate with numerous females. Such clever males make up less than 2% of the total population, but they are characterized by high productivity.
male, in front a female or male-faeders, which is indistinguishable from the female
Insects give each other gifts
“Love” and mating behavior in insects hide many fascinating secrets. Similar to the Hindu rituals of “Swayamvara”, where women chose their future husbands based on their strength, courage and fighting skills, female insects choose their mates based on their physical prowess and ability to survive. An interesting and familiar insect is the fruit fly. During mating, males gather around the female and begin to dance, vibrating their wings and their whole body in a certain way. Females choose a partner based on this dance.
Competition among males for a mate is not uncommon. Rhinoceros beetles whose males are endowed with horns on warm summer nights look for females. When he finds her, he tries to chase away other males with this horn. After successfully pushing away rivals, it proceeds to the female.
Who doesn’t like to get gifts from their other half? We are not alone in this. Insects also do this, sometimes at the risk of their own lives. Some species of flies of the genus Uncleidae receive gifts in the form of prey from their partners. If the female likes it, it willingly mates with the male, and at the same time feeds on the gift.
Peculiar physiognomy does not interfere with love
Steppe suhak – Saiga tatarica (Linnaeus, 1766) is an unusual antelope inhabiting Eastern Europe and Central Asia. In the Pleistocene, it also occurred in the Polish, as evidenced by bone remains discovered at 14 archaeological sites, m.in. in the Biśnik Cave, the Maszycka Cave and the Krucza Skała Shelter. It owes its characteristic appearance to the reduced nasal bone, which gives its nose a proboscis-like shape. The mating season begins in November – then males compete in the favor of females, and the winner leads a herd of 5 to 50 individuals. Females usually give birth to one or two offspring.
Competition for females also occurs in deer. The giant deer – Megaloceros giganteus (Blumenbach 1803) was one of the largest representatives of cervids, inhabiting Europe and Asia in the Pleistocene. Its impressive antlers reached almost 4 meters in span and weighed about 43 kg. It is calculated that during the growth period, which lasted about 150 days, the daily increase in the weight of the antlers was about 300 cm³, which allowed it to reach its full size. The breeding season began in autumn – then males competed for females, demonstrating their strength in spectacular fights and parades.
The victorious bull gathered a harem of several to a dozen or so hinds. After a pregnancy of about eight months, the female gave birth to one, rarely two fawns, which remained under her care until the next mating season. The skeleton of a deer can be seen at the exhibition at the Natural History Museum of the University of Wrocław.
Tamarin-style polyandry
Stories in which males have many partners are quite well-known, but this is not a rule, because it happens that females mate with several partners. For example, in tamarins, i.e. primates inhabiting South America, the common family system is 1+2+2. The female usually gives birth to two offspring, and due to the arboreal lifestyle, this is a complicated scenario. For this reason, the female chooses not one, but two partners who take care of the young equally during the day, while she returns at night to feed them. Thanks to this arrangement, the young are properly cared for, and any accidents related to falling from the tree are reduced to a minimum.
Faithful as a bird?
Although the ruffs are polygamous, it turns out that monogamy is the most common reproductive system in birds. This means that the male and female form a pair that together, although to varying degrees depending on sex, takes care of the brood. Why is monogamy so common in birds, and much less common in other groups of animals? This condition is explained by oviparity and endothermy of birds. The eggs they lay, but also the chicks, require intensive care. The care provided by two individuals from the pair allows to maintain the right temperature for the embryo developing in the egg as well as in young chicks, in which warm-bloodedness develops only after some time after hatching.
In birds, genetic monogamy and social monogamy are traditionally distinguished. Genetic monogamy is a situation in which partners are 100% faithful to each other. In the case of social monogamy, the offspring, usually a certain part of it, raised by a social couple, may come from a non-formal relationship, i.e. from the so-called extra-partner copulation. This system is most common in birds and is associated with the cryptic choice of the female, who chooses the male with the best evolutionary traits as the father of her chicks (depending on the hypothesis tested, it may be the highest, optimal or compatible genetic variation with the female). A situation in which a female is impregnated by a male from outside the social pair causes the social male to lose out on his own reproductive success, since he will invest energy in caring for the offspring of another male. A different, more evolutionarily sophisticated scenario is also possible. A female fertilized by a foreign male can lay an illegitimate egg in the nest of an amanta from outside the social pair (quasi-parasitism). Thus, in such a situation, the partner of an unfaithful male who will take care of the egg of a foreign female is exposed to evolutionary losses.
Monogamy is a very old evolutionary solution in birds. It remained in this group of animals probably due to its effectiveness in achieving reproductive success. However, it is believed that the original mating system in birds was mainly based on the care provided by the male, without the formation of bonds in pairs. This mating system is still present in the most primitive species of birds (Paleognathae) living today. Dual parental custody and monogamy emerged in the course of the evolution of the mating system, and polygamous systems evolved independently, most likely in response to specific ecological factors.
Courtship and arrows of snail Cupid
The sexual habits of snails are a mysterious and fascinating phenomenon, especially in the case of hermaphroditic species. They have both male and female reproductive organs, which means that each individual can play the role of male and female at the same time. During courtship, which sometimes lasts many hours, snails engage in subtle interactions. The couple recognizes each other by interacting with each other by smell and tasting mucus. The animals, circling around each other, touch each other with their antennae and gently rock each other to finally proceed to the act of love.
At this point, some species, such as the grape snail, use a love dart – a limestone dagger that is “shot” towards the partner and plays a key role in the love game and copulation itself. By burrowing into your partner’s body, it transmits hormones that stimulate sperm acceptance. This makes it easier to increase the number of fertilized eggs, thus improving the chances of reproductive success. The arrow can be “fired” by both snails at the same time or only one. These attempts are often unsuccessful, and it takes time to recreate the dart used. Therefore, not all love encounters take place with the use of arrows.
After a long and exhausting courtship, copulation itself finally occurs. Active partners, adhering to each other with the lower sides of the leg, nullify the penis, which transmits sperm packets (spermatophores) to the partner through the genital openings. Sometimes the sight of twisted copulatory organs protruding outwards is meaningful. For fertilization to be effective, snails remain in amorous stillness, for up to several hours. Just moments after separation, they can meet other potential partners again. Some of the sperm that have just been transferred is stored in a special seminal reservoir. They can then fertilize the eggs, although they will have to compete with the sperm of other copulatory partners, also kept in the same reservoir. Fertilization occurs only when it is time to lay eggs. This will happen provided that the environmental factors are favorable and the snail finds a sufficiently safe place to lay its eggs in the ground.
The entire mating ritual, which can be a symbol of patience and precision, is full of subtle gestures and non-obvious choices, in which the love dart becomes a tool not only for reproduction, but also for mate selection.
Delving into animal matrimonial stories, one conclusion comes to mind – love has many names and faces. What is important to us humans may be meaningless or have a completely different meaning for other species. As diverse as life on Earth is, so are the ways of building relationships. All kinds of love – whether human or animal – reflect an astounding variety of survival strategies in nature, so it’s worth admiring and appreciating their beauty, not just on Valentine’s Day.
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Stories about love in the animal world were told by:
dr hab. inż. Magdalena Zagalska-Neubauer, Department of Behavioral Ecology, Faculty of Biological Sciences, University of Wrocław
mgr Jakub Zając, Department of Behavioral Ecology, Faculty of Biological Sciences, University of Wrocław
dr hab. Małgorzata Proćków, Natural History Museum, Faculty of Biological Sciences, University of Wrocław
mgr Dominik Zięcina, Department of Biodiversity and Evolutionary Taxonomy, Faculty of Biological Sciences, University of Wrocław
dr Urszula Ratajczak-Skrzatek, Department of Paleozoology, Faculty of Biological Sciences, University of Wrocław
The text also includes materials from the following sources:
- Diversity: Evolutionary Ecology of Fixed Alternative Male Mating Strategies in the Ruff (Calidris pugnax)
- KQED: These Lizards Have Been Playing Rock-Paper-Scissors for 15 Million Years
- Dive Magazine
- Tańce, śpiewy i pokazy siły, czyli miłość w świecie owadów | Nauka w Polsce
- Love games that insects play | Resonance
- Ewolucja zwierzęcych prezentów godowych – ScienceDirect
Date of publication: 14.02.2025
Added by: E.K.
Translated by Zuzanna Łakoma (student of English Studies at the University of Wrocław) as part of the translation practice.
