P is for Photoreceptor

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As a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is P for Photoreceptor as illustrated by this male Eastern Carpenter Bee (Xylocopa virginica) from Maryland in the US.

“I’ve got my eyes, all five of them, on you!” This bee does indeed have five eyes: three ocelli (simple or single lens) which provide information on light intensity; and two compound eyes. Compound eyes are the principle visual organs of most insects; they are found in nearly all adults and in many immatures. As the name suggests, compound eyes are composed of many similar, closely-packed facets called ommatidia which are the structural and functional units of vision. The number of ommatidia varies considerably from species to species: some worker ants have fewer than six while some dragonflies may have more than 25,000. Each omatidium contains a photoreceptor cell which refracts incoming light down onto visual pigment which in turn absorb certain wavelengths of light and generate nerve impulses through a photochemical process similar to that of vertebrates and within a few milliseconds, sends it’s view of the image to the brain of the bee.

The brain combines all the images of these thousands of photoreceptor cells and forms a detailed picture of it’s subject in a sort of mosaic composition. Since insects cannot form a true (i.e. focused) image of the environment, their visual acuity is relatively poor compared to that of vertebrates but with each of these thousands of photoreceptor cells sending images to the brain, their ability to sense movement, by tracking objects from ommatidium to ommatidium, is superior to most other animals.

For more detailed information of photoreceptors in insects, take a deep breath and then jump into this article from North Carolina State University.

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O is for Opisthoglyphous

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As a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is O for Opisthoglyphousas illustrated by this pair of Small-spotted Cat-eye Snakes (Leptodeira septentrionali polysticta; Colubridae) from the Sittee River Wildlife Reserve in Stann Creek District, Belize.

The common name, Cat-eye, comes from this beautiful snake’s vertical pupils. It is a semi-arboreal species and a mildly venomous hunter of frogs and toads and their eggs and tadpoles. Bearing in mind that all snakes, in fact all wild animals, should only be handled in very specific circumstances and only by someone with the proper experience and expertise, this is a very calm and docile animal when being handled.

It poses very little threat to humans because unlike the venomous elapids (including coral snakes) with forward-grooved fangs (proteroglyphous) and the venomous vipers (lanceheads like the Fer-de-Lance, rattlesnakes, bushmasters, and pit vipers) with pipe-grooved fangs (solenoglyphous), this species is what is known as “opisthoglyphous” or rearward-grooved.

In opisthoglyphous snakes, their venom is injected by a pair of enlarged teeth at the back of the jaws which normally angle backwards and are grooved to channel venom into the puncture. Since these fangs are not located at the front of the mouth this arrangement is vernacularly called “rear-fanged”. In order to envenomate prey, an opisthoglyphous snake must move the prey into the rear of its mouth and then penetrate it with its fangs, presenting difficulties with large prey, although they can quickly move smaller prey into position.

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Native or native “cultivar”, what to do?

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Native vs native “cultivar”, what to do? Just something to ponder as I post here 5 different cultivars of Phlox subulata (“native” to the eastern US).

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I’ve designed and built over 600 gardens around the world, almost exclusively “conservation” gardens where the only plants used are natives and endemic to that specific region, or children’s gardens where other considerations such as color, scent, texture, relative toxicity are priorities.

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However sourcing native species from a vendor can be troublesome, not just because of where the actual material originated (the genetics of two different geographical populations of the same species can vary quite markedly) and how it was propagated (about 70% of natives are genetic clones), but also because one has to make the decision as to whether or not the “cultivar” of a native still retains what made it “native” to begin with (read: ecological role).

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For a further discussion, this article from the team at Native Plants and Wildlife Gardens is a pretty good start.

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Also known as Moss Pink, marking the advent of early Springtime flowers, this species lends its name to the full moon every April as the Pink Moon.

N is for Nectar-Robbery

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As a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is N for Nectar-robbery as illustrated by this “Culo-de-vaca” stingless bee (Trigona fulviventris; Meloponini); Sittee River Wildlife Reserve, Stann Creek District, Belize.

Pollination systems are mostly mutualistic, meaning that the plant benefits from a pollinator’s transport of male gametes to the female organs on another flower and in return, the pollinator benefits from a reward such as pollen or nectar. However in some cases, as in this “culo-de-vaca” bee, which is a short-tongued bee, and this tubular-flowered Firebush (Hamelia patens; Rubiaceae), the bee cannot extend its tongue far enough to get at the nectar by entering the flower from its open end, so it bypasses the anthers of the bloom by biting a hole at the base of the flower to get easier access- the term used is “nectar-robbery” because the flower is not rewarded by being pollinated!

It is interesting to note that this particular species of bee has been documented to demonstrate spatio-temporal (also called time-place) learning behavior, the ability of some individuals in the colony to associate the time and place of an event such as when nectar is flowing, anticipating successful nectar gathering by arriving up to 30 mins ahead of a feeding event and staying as much as 30 mins after it was “scheduled” to be available.

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short-tongued Meliponine bees committing nectar-robbery on a Morning Glory

M is for Myrmecomorphy

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As a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is M for Myrmecomorphy. What scurries like an ant but jumps like a grasshopper? This ant-mimic oprthopteran (Gryllidae) found in the Sittee River Wildlife Reserve, Stann Creek District, Belize!

Batesian mimics are species which typically lack strong defences of their own, and make use of their resemblance to well-defended ants to avoid being attacked by their predators, some of which may even in fact be ants. As ants are often either unpalatable or aggressive, looking like an ant is useful for non-ant organisms when evading many of the predators that hunt that vision so having an ant shape and demonstrating convincing antlike behaviour like our photo subject for today is a good strategy- this mimicry is called “myrmecomorphy” derived from the Greek with “murmex” (μύρμηξ) meaning “ant” and “morphe” (μορφή) meaning “form” or “shape.”

For a little more information on myrmecomorphy, check out this blog post by Georgia Kelly from James Cook University in Australia

And for more photos and natural history of ant mimics, here are some from ant expert and the Curator of Entomology at the University of Texas/Austin, Alex Wild

L is for Labriform

dive-21-eighteenth-palm-shore-dive-max-depth-50-feet-bottom-time-50-mins---the-critically-endangered-hawksbill-sea-turtle-eretmochelys-imbricata-bonaire-dutch-caribbean_19005762414_o.jpgAs a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is L for Labriform, as illustrated by this endangered Hawksbill Turtle (Eretmochelys imbricata)

These guys appear to be so laid back, flying past you in a gentle arc inviting you to follow as they cruise the reef in search of sponges, squid, and shrimp. As they glide smoothly through the water, their front flippers are turned like those of an aircraft so that drag is minimized but when propulsion is needed, they use their flippers in a sort of rowing action. There are a number of studies of fish, reptiles, and mammals that suggest that flapping paired appendages (fins or flippers) around a rigid-body is an extremely efficient form of locomotion and include research into wrasses and parrotfish, penguins, and sea lions, as well as sea turtles. This form of aquatic locomotion is termed “labriform.”

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K is for Kleptoplasty

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As a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is K for Kleptoplasty, as illustrated by this Lettuce Sea Slug (Elysia crispata) from Bonaire in the Dutch Caribbean.

Looking a little bit like a frilly lettuce, hence its common name, this species lives in the tropical parts of the western Atlantic, and the Caribbean where it is found in more coastal and tropical reef areas where the water is shallow and clear. Like its snail relatives, Elysia crispata uses a rasping organ (radula) to cut into its food- in this case a number of species of green algae, but what it does with its food is rather unique!

While feeding on algae, it will digest almost all of the tissue except for the chloroplasts. This amazing adaptation is termed “kleptoplasty”, derived from “kleptes” (κλέπτης) which is the Greek for “thief”. Chloroplasts are not found in animals but only within the cells of plants and certain protists such as algae and are responsible for harnessing light during the photosynthesis process. After ingesting them, the Lettuce Sea Slug is then able to distribute the chloroplasts throughout the surface of the tissues of its body where they will continue to photosynthesize thus producing sugars which provides the living energy for this unique animal!

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