Skip to main content

#33: Hamuli

A row of hamuli on the wing of a bee


The top two hamuli shown here are hooked onto the
back edge of the forewing.

Litinsects #33: Hamuli

Today’s post is another on anatomy and is about a structure found in a group of insects that probably everyone around the world is familiar with...

The order HYMENOPTERA is comprised of bees, wasps, sawflies, and ants. (Yes, ants are actually related to bees and wasps.) At around 150,000 described species it is among the top 4 largest group of insects (along with beetles, flies, and butterflies).

One defining characteristic of hymenopterans are HAMULI (see photos). Hamuli (singular hamulus) are microscopic hook-like structures on the front surface of the rear wing that hook into the back edge of the front wing. This system interlocks the two wing pairs during flight, allowing them to beat in unison and act as one functional pair of wings. Basically hymenopterans have developed an anatomical wing coupling feature to enhance flight efficiency. (In the third photo you can see the top two hamuli hooked into the fore wing!)

The reason I wanted to explain hamuli is because there is a cool tie-in as to why this group is named hymenoptera. Two explanations exist for the etymology of the word; we already know the second part of the word refers to the wings, but what about the first part?

(1) “Membrane-winged”: The Greek word “hymen” means membrane, which makes sense since they have relatively few wing veins compared to other groups.

(2) “Married wings”: Now that we know what hamuli are, the second explanation makes sense as well: Hymeno is the Greek god of marriage so the name might also be a reference to the fact that the wings are “joined together” in flight.

While we’re on the subject, I wanted to share another cool feature of the group: the system of sex-determination, known as HAPLODIPLOIDY. In hymenopterans, sex of offspring is determined by how many sets of chromosomes they have. Unfertilized eggs contain only 1 set (the chromosomes from the mother) and develop into males, while fertilized eggs contain 2 sets (one from each parent) and develop into females. What is quite interesting is that egg-laying mothers actually have control over the sex ratios of their offspring. As an egg is laid, a muscular ring at the end of the sperm duct controls whether a sperm is let through or not.
Labels:

Comments

Post a Comment

Popular posts from this blog

#4: Simple Eyes

Litinsects #4: Simple Eyes Yesterday I talked about compound eyes, the multi-faceted structures that most insects use to see the world 👀 But insects actually have another visual system as well, composed of simple eyes or OCELLI. Unlike compound eyes, ocelli are composed of only one structure which makes them comparatively “simple” although they are still very important. These are light-detecting organs consisting of a single lens with sensory cells. They can detect movement but don’t form complex images. “Ocellus” comes from the Latin word oculus, meaning eye. So these structures are literally “little eyes” Ocelli are located on the insect’s head, usually between or adjacent to the compound eyes. They are usually dome-shaped, somewhat shiny structures In most flying insects (such as flies, dragonflies, bees, etc.) there tend to be three ocelli in a triangle arrangement (see photo). Some terrestrial insects (like cockroaches) have only two ocelli ...
Post a Comment
Read more

#34: Insect Wings

Dragonfly wings Dipteran (fly) wing Monarch butterfly wing Lacewing wings Litinsects #34: Insect Wings Let’s talk wings. The ability to fly has existed in only 4 groups of animals: birds , bats , pterosaurs , and of course insects . The first three groups, all vertebrates, each evolved flight independently (in other words, they have no winged ancestor in common) and the wings replace a pair of limbs. Insect wings on the other hand, which first showed up around 400 million years ago, are not derived from legs but are completely separate structures. The big debate about the evolution of insect wings is whether they developed from pre-existing structures (like gills or extensions of the thorax) or were entirely new structures. There is very little fossil evidence documenting this evolutionary transition so no one has yet definitively answered this question... Insect wings attach to the second and third thoracic segments. At rest they may be held vertically over the back, horizontally ou...
Post a Comment
Read more

#51: Mayflies

Litinsects #51: Mayflies Mayflies are aquatic freshwater insects and belong to one of the most primitive winged insect lineages! First off, what’s in a name? Mayflies’ common name comes from the fact that some species start “hatching” from the water in May. But their scientific name is much more interesting and accurate; this order is named EPHEMEROPTERA from the Greek “ephemera” for “lasting one day / temporary” and “pteron” for “wing”. A more fitting name would be dayfly, considering their adult lifespan... Most live less than 24 hours after emerging, the shortest adult lifespan of any insect! -Mayflies have triangular-shaped wings that are held upright over their bodies when at rest (sort of like a butterfly) and have three long tail-like filaments. These characteristics, both of which make them easily recognizable, are probably traits that were present in the most primitive flying insects -They are HEMIMETABOLOUS insects, meaning they go through incomplete metamorphosis, with multi...
Post a Comment
Read more