Tuesday, April 30, 2019

Insect Taxonomy -- April 30, 2019

Anyone interested in natural history, run, don't walk to your nearest bookstore or surf over to Amazon and buy Natural Histories Innumerable Insects: The Story of the Most Diverse and Myriad Animals on Earth, Michael S. Engel, c. 2018.

So, many, many sub-phylum/clades of the large phylum Chordata.

Of one of the sub-phyla of chordata, there exists Hexapoda.

Within hexapoda: only two classes: the Entognatha (wingless, obscure; primitive, ignored; and Insecta (includes a few wingless insects and two general types of winged insects).

  • Chordata (phylum)
    • Hexapoda (clade; sub-phylum)
      • Entognatha (class): Diplura, Proture, & Collembola (orders)
  • Diplura: 1,000 species
  • Protura: 500 species
  • Collembola: 9,000 species
These are the only three orders of hexapoda that are not considered true insects.

All the rest of the orders of hexapoda are considered true insects (Insecta)
      • Insecta (class)
First true insects: Archaeognatha and Zygentoma (bristletails and silverfish). Like the entognathans: wingless, widespread, and mostly ignored. Wingless; taxonomy determined by mouth:
          • Archaeognatha (order): bristletail
          • Zygentoma (order): "yoke." Silvertails. The yoke/bridge between the wingless insects and the winged insects.
Primitive, winged. One general sub-class of the

Except for preceding wingless Insecta (bristletails and silvertails), all living insects belong to a hefty subclass called the Pterygota.
        • Pterygota (sub-class) -- remember, class determined by presence/absence specialized jaw that ants have;
Holometabolism: complete metamorphosis.

I believe the following orders do not undergo complete metamorphosis:
          • Ephemeroptera (order)
          • Odonata (order)
          • Plecoptera (order)
          • Embiodea (order)
          • Zoraptera (order)
          • Notoptera (order)
          • Dermaptera (order)
          • Orthoptera (order)
          • Phasmatodea (order)
          • Mantodea (order)
          • Blattaria (order)
          • Isoptera (order)
          • Psocodea (order)
          • Thysanoptera (order)
          • Hemiptera (order)
Complete metamorphosis; homometabolos; most diverse groups of winged insects
  • Megaloptera (order)
  • Raphidioptera (order)
  • Neuroptera (order)
  • Coleoptera (order)
  • Strepsiptera (order)
  • Hymenoptera (order)
  • Mecoptera (order) -- relict; 750 species
  • Siphonaptera (order)
  • Diptera (order)
  • Trichoptera (order)
  • Lepidoptera (order)
So, it looks like, if "phylum" means body type, then chordata is a body type, and the sub-phylum hexapoda is a body type.

Then comes class. Class must be a member of a body form but distinct from other types of body forms found in the sub-phylum of hexapoda. The two classes in this phylum are Entognatha and Insecta.

Among the class Insecta, there is one sub-class (this is all the extant Insecta) so if there are other sub-classes of Insecta, they must be extinct.

In the sub-class of the living Insecta, called the Pterygota -- all have wings. 

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October 13, 2019
Review: Kingdom --> Class

So, let's review.

Insects (CLASS).

Kingdom: animalia, obviously

Phylum: body type -- obviously chordata
Sub-phylum: still within body type -- now we have hexapoda

Class: must be of the "body form" of chordata / hexapoda but "classes" are variations with the body type

It appears there are to major chordata/hexapod, based on jaw type. When anatomists looked at the six-legged chordata, they said what distinguishes them? Their jaws. Hexapod classes based on jaws.
  • entognatha
  • insecta
So, we go from chordata with six legs vs chordata without six legs, and then among the "six-legs," we separate hexpods based on jaws.

"Archaic" hexapods had "internal jaws," the entognatha.

But the "insecta," the insects, had very, very interesting modified jaws.

And now that we have reached insecta/insects, we are at the class level.

It looks like sub-class based on presence/absence of wings (Pterygota).

Below the class level: orders, families, genus and species.

Orders: it appears orders are then based on wings.

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Metamorphosis

It appears the book will now go to two chapters:
  • those orders with incomplete metamorphosis
  • those orders with complete metamorphosis (holometabolism)
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Moving Toward Orders (Wings)

This chapter will be those orders that do not have complete metamorphosis?

Wings, but also molting, which was probably sorted out later.

Among the Insecta/insects, winged and wingless.

So, perhaps orders will be sorted out by wings. It looks like that when you look at the names of the various insects; it seems most of the orders have "ptera" in their name;

First, wingless orders -- hexapods with specialized jaws (Class: Insecta) without wings:
  • bristletails
  • silverfish
  • probably best examples of what the ancestor all insects might have looked like
  • like most entognathans, bristletails and silverfish molt continuously throughout life; 
  • by contrast, all other Insecta stop molting after reaching maturity (with one notable exception to be highlighted later)
Entognathans, bristletails, silverfish (not considered "true insects" -- see page 31)
  • wingless
  • molt continuously
  • copulate? no
Again, we are the level of:
  • class: chordates with six-legs defined by their jaws
  • sub-class: a little mess but pretty much wingless
When we get to order, it appears we may be looking at insects based on wings.

On page 38, we get to the "first true insects."

Note: bristletails and silverfish pre-date true insects; have no wings; molt continuously throughout life; and do not copulate

Now, back to "true insects":
  • chordates with six legs, specialized jaws, and with wings (some of which have lost thier wings)
  • stop molting at maturity
  • copulate
Oldest orders:
  • archaeognatha (again, "old jaws"): bristletails
  • zygentoma: silverfish or firebrats
Zygentoma (silverfish) "yoke" or "bridge between wingless insects and winged insects (p. 41)

End of chapter.

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Chapter 4 
Winged Insects

I believe the following orders do not undergo complete metamorphosis:
  • Ephemeroptera (order): mayflies
  • Odonata (order): dragonflies, damselflies
  • Plecoptera (order): stoneflies
  • Embiodea (order): webspinners (not spiders)
  • Zoraptera (order): so recently discovered (1913), no common name
  • Notoptera (order): classified in 1915; ice crawlers in the north western hemisphere; rock crawler of the sub-Sahara
  • Dermaptera (order): earwigs; ugly things we see everywhere;
  • Orthoptera (order): grasshoppers, crickets, katydids
  • Phasmatodea (order): stick and leaf insects; masters of disguise
  • Mantodea (order): mantisas
  • Blattaria (order): roaches
  • Isoptera (order): termites
  • Psocodea (order): lice (bark lice and true lice)
  • Thysanoptera (order): thrips
  • Hemiptera (order): aphids, whiteflies, scale insects, planthoppers, cicadas, lantern bugs and true bugs
Hemiptera: the first of the truly megadiverse lineages with slightly over one hundred thousand species.

Wings part of the diversity of insects and their success; but wings are over-emphasized.

The chapter ends: In reality, it is the coming together ofmany evolutionary factors -- an interaction of several key traits in combination with the wider environment, stochastic events, and the concomitant evolution of other lineages -- that breeds diversity. For insect diversity, a significant change subsquent to the origin of wings metamorphosed a large gropu of flying insects into evolutionary superpowers, with true hegemony over our world.

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Chapter 5
Complete Metamorphosis


Holometabolous insects account for the real bulk of insect diversity, with approximately 85% of all insects undergoing complete metamorphosis. 

Complete metamorphosis; homometabolos; most diverse groups of winged insects
  • Megaloptera (order): dobsonflies (380 species)
  • Raphidioptera (order): snakeflies (250 species)
  • Neuroptera (order): lacewings; (5,800 species); relicts
  • Coleoptera (order): the beetles; the behemoths of insect diversity, over 360,000 described species and a steady stream of new species flowign in every year;
  • Strepsiptera (order): twisted-wings (600 species)
  • Hymenoptera (order): ants, bees, and wasps (over 155,000 species); wasps? think parasitism
  • Mecoptera (order) -- relict; 750 species; scorpionflies; earwigflies (only 3 surviving species)
  • Siphonaptera (order): fleas (siphon: piercing, sucking stylets; "a" -- without; ptera - wings;
  • Diptera (order): true flies as well as as mosquitos and midges; two wings; flies are unusually successful with over 155,000 species discovered, but this might be only a quarter or less of their global diversity;
  • Trichoptera (order): caddisflies (14,000 species)
  • Lepidoptera (order): butterflies and moths (157,000 species; by far the most diverse group of plant-feeding insects; Greek lepidos means scales; butterflies are nothing more than garish, day-flying moths, comprising about 18,800 species;
All orders have a thousand species or less except for four mega-diverse orders, each with 100,000 species or more.

Who discovered that larvae and adult flying insects were one and the same? Swammerdam and Merian.

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Chapter 6
Pests, Parasites, and Plagues

Fleas and lice
Kissing bugs, tsetse flies, and mosquitoes
Bed bugs and maggots
Locusts and other herbivores
Weevils

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Chapter 7
It Takes A Village

Insect architecture
Ants and termites
Squatters and farmers

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Chapter 8
The Language of Insects

Chemical signals
Movement and light, vibration and sound
The dance of the honeybees

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Chapter 9
Hiding in Plain Sight

Camouflage
Mimesis

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Chapter 10
The World Abloom

Nectar, fragrance, and warmth
Specialization















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