THE SNAIL’S LOVE DART
When we talk about competition for mates, we often think of behaviors involving tense fights or flamboyant displays of traits that signal quality. However, sometimes the competition continues even after mating, as the sperm must outcompete sperm from other mates.
In land snails of the families Helicidae and Ariophantidae, this post-copulatory competition involves the injection of a calcium-based “love dart”. These snails are simultaneous hermaphrodites, so during mating, both partners can act as male and female, leading to …
WHEN ANTS GET CLOSE…WHAT DO THEY EXCHANGE?
Ants are social insects, well known for their division of labor and caste systems, as well as their hardworking nature. They have also inspired popular culture, including sayings (“ants in your pants”), music (see “Ants marching” and “El hormiguero”), and jewelry. However, there is one curious behavior that is largely unknown to the general public (and even to many scientists) called trophallaxis, in which ants ingest liquid shared by another individual! This can occur in two different ways: as a regurgitate coming from the mouth, called stomodeal trophallaxis, or as an excretion from the rectal end of the abdomen, called proctodeal trophallaxis. Trophallaxis also occurs in earwigs, burying beetles, birds, and mammals, but we will focus on ants, an extensively studied group.
In a comprehensive review, Meurville & LeBoeuf (2021) describe how within ant colonies, trophallactic behavior occurs in multiple directions …
WHEN YOUR VERY FIRST MEAL IS YOUR SIBLING
Nature never stops amazing us with the incredible diversity of parental strategies that have evolved to increase offspring survival. During development, mothers provide nutrients to their young in different ways, usually through a placenta, maternal tissues, or yolk stored in the egg. But, can you believe that there is an extreme case in which the food that mothers provide is the siblings that are sharing the same maternal space? This phenomenon, known as adelphophagy, is relatively rare in the animal kingdom, but has been documented in vertebrates such as sharks, as well as in invertebrates like echinoderms, insects, molluscs, and annelids.
Maternal feeding of siblings also occurs in two types of invertebrates that are unfamiliar to many of us: flatworms and ribbon worms. Both are…
IS THE HEALTH OF THE OFFSPRING REALLY ONLY THE MOTHER’S RESPONSIBILITY?
Decades of research have been dedicated to link the mother’s health and nutritional habits with the health of their children in both the short and the long term. And yes, it is important of course! However, what do we know about the effect of the father’s nutritional habits? Is the father’s only job really to contribute sperm to fertilize the egg? In short, the answers are “yes” and “no”. Yes, because the nutritional habits of the father also affect the offspring. And no, because the sperm does not only contribute genetic material, but also play a fundamental role in fetal and child development.
In an elegant review, Skerrett-Byrne and colleagues (2025) remind us that sperm is far from being only a passive DNA carrier, but rather is an epigenetically active player …
TOXIC SEX: WHEN POISON BECOMES A GIFT
Blister beetles, as their name suggests, are beetles of the Meloidae family known for causing blisters upon contact with human skin. Toxicity in these coleopterans is due to the presence of a defensive chemical compound in their hemolymph called cantharidin, which is known to be toxic to mammals, birds, and frogs. Cantharidin has fascinated scientists and human societies alike for centuries and has a long history in both scientific and popular literature.
Female blister beetles contain less cantharidin than males. They are unable to synthesize it themselves, but the way that they acquire it is fascinating: they…
AN OVIPAROUS CAECILIAN FEEDS ON OVIDUCTAL MILK
When you think about amphibians, caecilians are probably not the first animals that come to mind. They are among the most poorly understood amphibians, largely due to their fossorial lifestyle. Classified in the order Gymnophiona, they differ from frogs and salamanders because they are limbless and elongated, resembling snakes or worms more than a “typical” amphibian.
Despite their secretive nature, researchers have documented interesting parental feeding mechanisms, such as…
MILK PROVISIONING IN TSETSE FLIES
You probably have heard about the tsetse fly, the African fly which feeds on blood of both humans and animals. They are a troubling public health concern because they are vectors of African trypanosomes. However, tsetse flies are also known for something else - something extraordinary.
Similar to humans, tsetse flies possess milk glands! Mother flies give birth to live young, after larvae develop inside of their uterus. To nourish their larvae …
ORAL SEX IN SPIDERS
When we think about sexual rituals in insects, perhaps the first things that come to mind are sexual cannibalism of males by females, nuptial gifts from males to females, opportunistic mating, pair bonding, genital mutilation, or plugging. All of these, while impressive, are relatively well documented.
But, in 2016, Gregoric and colleagues studied the sexual behavior of the Darwin's bark spider from Madagascar …
FEEDING ON SLIME
Velvet worms are among the most extraordinary animals on earth! With a very simple body structure, these ancient animals have been living on our planet for nearly 500 million years. Despite their name, they are not actually worms. They are not insects either, but look like caterpillars, and belong to their own phylum called Onycophora.
Onycophorans have a remarkable technique for hunting. To capture their prey, velvet worms eject a sticky, adhesive slime from their oral papillae, which are located close to their mouth. The sticky slime immobilizes the prey so that the velvet worm can then casually approach it.
In a study of feeding behavior conducted in Costa Rica in 2019, researchers documented for the first time a form of parental feeding in velvet worms...