Phylum

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Major Aquatic Invertebrate Taxa
Phylum Porifera (sponges) Cnidaria (hydra
jellyfish) Platyhelminthes (flatworms) Gastrotr
icha (gastrotrichs) Rotifera (rotifers) Nematoda
(nematodes) Mollusca (snails/bivalves) Annelida
(oligochaetes/leeches) Arthropoda (arthropods)
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Phylogeny of aquatic insects
Paleozoic Mesozoic Cenozoic
mayflies
dragonfly
stoneflies
bugs
beetles
fishflies lacewings
caddisflies
flies
moths
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Phylum Arthropoda Subphylum Chelicerata Class
Arachnida Subphylum Uniramia Class
Insecta Subphylum Crustacea Class
Malacostraca Class Ostracoda Class
Branchiopoda Class Copepoda
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Subphylum Uniramia
Class Insecta Order Ephemeroptera (mayflies) Order
Plecoptera (stoneflies) Order Odonata (dragon/da
mselflies) Order Trichoptera (caddisflies) Order
Megaloptera (alderflies) Order Hemiptera (true
bugs) Order Coleoptera (beetles) Order
Neuroptera (spongillaflies) Order
Lepidoptera (caterpillars) Order Diptera (flies
and midges) Order Collembola (spring tails)
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Arthropods
--most successful of all invertebrate taxaby
far! --about 1 million species --nearly all are
dioecious --cilia are universally absent --most
prominent adaptive characteristics 1)
exoskeleton 2) paired appendages 3)
cephalization
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Exoskeleton
--Cuticle a) nonliving, organic complex
produced by epidermis. b) composed primarily of
recalcitrant chitin. c) also contains lipids,
waxes, carbonate, pigments. d) melanin pigments
deposited in the cuticle create different colors
(breeding, protection, etc..). e) iridescence
is not due to pigments, rather it results from
fine striations on surface of cuticle.
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• Hardening of exoskeleton caused by
• Schlerotization restructuring of insoluble
  proteins
• Calcification deposition of calcium carbonate
  (calcite) in the cuticle.

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General anatomy, physiology, and development of
insects
-- About 1 million species --12
aquatic/semiaquatic orders

• 3 distinct regions
• head sensory perception, neural integration,
  food gathering.
• Thorax locomotion
• Abdomen houses visceral organs (digestive,
  excretory, reproductive systems)

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Body wall

• Cuticle (exo- and endo-)
• Epidermas
• Basement layer

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Abdomen
--Generally composed of 11 metameres --Each
metamere composed of dorsally sclerite
(tergum) ventrally sclerite (sternum) laterall
y membranous (pleuron) --Genitalia located on
8-9 segment
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Thorax
Composed of 3 segments 1) anterior
prothorax 2) middle mesothorax 3) posterior
-- metathroax
Legs
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Head
Important external features 1) Antennae --
contain chemical, olfactory, tactile, and
auditory receptors. Can also sense
vibrations. 2) Compound eyes (vision/movement/colo
r) and dorsal ocelli (light detection). Many
insects perceive ultraviolet, blue-green and red
wavelengths. 3) Specialized mouth parts food
gathering, defense.
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Head Mouthparts
2 general types 1) mandibulate specialized
for biting off and chewing food (most nymphs) 2)
haustellate specially adapted for piercing and
sucking (e.g. mosquitoes and dipterans).
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Head Antennae
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Digestive system
Mouth Pharynx Esophogus Crop (stores
food) Gizzard (denticles help macerate
food) Stomach Pyloric valve Pylorus Intestine
(water reabsorption) rectum
foregut
midgut
hindgut
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Circulatory System
Open circulatory system a) Capillaries are
absent. Blood flows through hemocoelic spaces
(bathes internal organs) b) Insect blood is
relatively clear and contains hemocytes
(analogous to WBC).
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Excretory System
--Malpighian tubules (2-150) distal ends free in
hemocoel. -- Uric acid in hemolymph combines with
potasium bicarbonate to form potassium acid
urate. -- PAU taken up by Malpighian tubules,
reabsorb Potassium bicarb. and excrete
crystalline uric acid as a dry pellet.
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Metamorphosis

• -- Subclass Apterygota (ametamorphic)
• -- Subclass Pterygota (2 types of metamorphosis)
• Exopterygotes (wings develop externally in later
  nymph stages). Undergo simple or incomplete
  metamorphosis termed hemimetabolous.
• (e.g. odonata, hemiptera)
• Endoterygotes (wings develop internally during
  larval stages). Undergo complete metamorphosis
  termed holometabolous.
• (e.g. coleoptera, trichoptera, diptera)

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Aquatic Insects
10 aquatic orders 5 have larvae that are
almost entirely aquatic Ephemeroptera Odonata
Plecoptera Trichoptera Megaloptera 5 are
partially aquatic Heteroptera Coleoptera Dip
tera Lepidoptera Neuroptera
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Metamorphosis
1) Hemimetabolous life cycle includes 3
developmental stages egg, larva and adult. Most
larva (except Plecoptera) do not resemble
adults. Ephemeroptera, Odonata, and
Plecoptera 2) Holometabolous life cycle
includes 4 developmental stages egg, larva,
pupa, and adult. Larva do not resemble
adults. Trichoptera and Megaloptera Coleopte
ra, Diptera, Lepidoptera, Neuroptera
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3) A paurometabolous life cycle includes 3
stages egg, nymph, and adult. Nymphs live in
same habitat and resemble adults. Heteroptera
(Hemiptera)
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Metamorphosis
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Some interesting scientific names
Colon rectum (leiodid beetle)
Godzillius, Pleomothra (remipede crustaceans)
Some very long scientific names
Parastratiosphecomyia stratiosphecomyioides (a
dipteran)
Gymnometriocnemus kamimegavirgus (a chironomid)
Gammaracanthuskytodermogammarus
loricatobaicalensis (an amphipod)