Lab 8: Arthropoda OEB 51 Lab 8: Arthropoda 6 April 2016 ATTENTION: Today we will be examining several preserved specimens from along the arthropod diversity and some exciting live specimens that you have not seen in the fieldtrip! Please keep all preserved specimens submerged. Examine using forceps and probes – be careful not to damage or remove the limbs of any specimen. And remember to return the specimen to its original spot in the lateral bench so your friends can find the animals properly labeled. • For each specimen, even when specific instructions are not given, make detailed observations and drawings and take notes on important characters in the evolution of arthropods, such as tagmata and adaptations to the specific environment where the organism lives. 1 Lab 8: Arthropoda OEB 51 Myriapoda With these living myriapods, take the opportunity to make a few notes on behavior – locomotory, hygienic (they frequently clean their antennae). CHOOSE ONE • Chilopoda (live) Do not handle these centipedes directly, as they are venomous (not deadly, but still). Watch these animals move, but don’t let them escape! Try to draw if you can. Compare to the large, preserved Scolopendra gigantea (MCZ specimen). Draw from the preserved for more morphological details. • Diplopoda (live) Contrary to centipedes, millipedes are docile (but they have deterrent substances, like cyanide compounds, which you might be able to smell after handling the specimens). Observe their movement. Make a sketch of the whole body and drawings of specific parts in more detail. • What is the most conspicuous difference between these two groups of myriapods? 2 Lab 8: Arthropoda OEB 51 Pycnogonida •
Colossendeis colossea (Museum specimens, handle with care) •
What characteristics of pycnogonids are not found in other arthropods? 3 Lab 8: Arthropoda OEB 51 Chelicerata CHOOSE ONE •
Xiphosura – Limulus (horseshoe crab). •
Arachnida – Chelicerates with 4 pairs of legs (some not used for walking). Opiliones (Harvestmen) Uropygi (Vinegaroons/whip scorpions) Scorpiones (Scorpions) – Live Pandinus imperator! (Tauana will demonstrate the baby emperor scorpion glowing under UV light! – Observe the sclerites and articular membranes). Also check the preserved P. dictator for morphological details. Amblypygi (the ‘spider’ used in Harry Potter and the Prisoner of Azkaban is actually a harmless amblypygid [or whip-­‐spider]!) Solifugae – Sometimes called sun spiders, these large arachnids are not closely related to spiders at all. Their chelicerae are extremely large. Pseudoscorpiones (Pseudoscorpions) – Live! And preserved. These tiny arachnids live in humid soils and cryptic habitats, where they prey on microfauna. They often engage in phoretic behavior, using other arthropods (often flying insects) as a means of dispersing long distances. Araneae (Spiders) – Live Brachypelma smithi! (Courtesy of Patrick Gorring, Graduate student in the Farrell Lab) – Do not open its cage! Rather than bite, this Mexican red-­‐kneed tarantula will kick urticating hairs from its abdomen and from the back legs if disturbed. 4 Lab 8: Arthropoda OEB 51 Crustacea – Arthropods with biramous limbs and nauplius larvae. •
Malacostraca
Isopoda – Isopods are usually small, with marine, freshwater and terrestrial (pillbugs) species. CHOOSE That said, look at our giant deep-­‐sea isopod (Bathynomus giganteus)! And they can get even larger! ONE Amphipoda – Caprellidea (Skeleton shrimps) and Gammaridea. Not true shrimps at all (check decapods below). You might have seen live ones in the algae or hydroid colonies in Panama or even other labs. Decapoda – The crustaceans with five pairs of locomotory appendages. Includes crayfish, crabs, lobsters, prawns and shrimps. Caridea – True shrimps Astacidea – Lobsters – Live! Also look at the mouth parts to see Cycliophorans! Achelata – (“Missing claws”) Includes spiny, slipper lobsters and furry lobsters Brachyura – True crabs, they have their abdomen completely hidden under the thorax. Can you identify both sexes? How? (Illustrate in your drawings) Panulirus – Spiny lobster Uca pugilator – Sand fiddler crab. Look at the difference in size between the claws. What could that be for? Can you identify sexes? How? What is in the pleon?! Stomatopoda Squilla – Mantis shrimp – Not a true shrimp as the decapod Caridea (above) • Maxillopoda Cirripedia – Barnacles and kin. Check out the strange morphology of this goose barnacle! DRAWING SPACE FOR CRUSTACEANS ON NEXT PAGE! 5 Lab 8: Arthropoda OEB 51 6 Lab 8: Arthropoda OEB 51 Crustacea •
CHOOSE ONE Hexapoda – Don’t forget that, although often treated in separate due to all their diversity and modifications, hexapods (and hence its subgroup, insects) are nothing more than crustaceans that invaded land! What are some potential reasons for their enormous success in this environment? We will observe most of the diversity of the group in our visit to the arthropod section of the HMNH next week, but we have a few representatives here for you to take a closer look. Blattodea – Live Gromphadorhina! You can see tons of these Madagascar hissing cockroaches at the Ernst Mayr Library (Dorothy is responsible for them!). When you go there, look for the very pale, soft-­‐bodied individuals – they recently molted and don’t have their cuticle darkened and hardened yet! The ones we have today are courtesy of Caitlin Baker, Graduate student at the Giribet Lab. Orthoptera – Preserved grasshoppers. 7 Lab 8: Arthropoda OEB 51 Cycliophora Symbion live on the mouthparts of lobsters. Today we have a lobster and luckily we will find many cycliophorans on it. The cycliophoran body is divided into an anterior buccal funnel, an oval trunk, and a posterior acellular stalk and adhesive disc by which the animal attaches itself to setae on the host's mouthparts. They are suspension feeders, obtaining food by creating water currents with dense cilia around the buccal funnel. The U-­‐shaped gut is ciliated along its entire length, ending with an anus located near the base of the buccal funnel. Circulation and gas exchange are presumably accomplished by simple diffusion. ARTICLE IN PRESS
86
M. Obst et al. / Organisms, Diversity & Evolution 6 (2006) 83–9
dehydrated in an aceto
propylene oxide, and s
812 . Ultrathin secti
acetate and lead citrat
examined and microgra
MORGAGNI 268 TE
Taxonomic section
-Phylum Cycliophor
-Class Eucycliophor
-Order Symbiida Fu
-Family Symbiidae F
-Genus Symbion Fu
species: Symbion pan
1995)
Symbion americanus
.
Etymology
The species epithet
with that of the host, H
Make your representation of a cycliophoran you observed: the masculine gender
the genus name.
Type material
Holotype: feeding in
ZMUC) from sample
44123 N, 68102 W, 8
mounts,
CYC
23
61718–61722; TEM se
all life stages except fo
larvae, found on mo
collected as sample 1.
Additional material
All life cycle stages,
near Domariscotta, M
observations in Boston
2001; Sample 4: Ca
Massachusetts, Octobe
Maine (type locality
observations in Stockh
Maine, August 2004. S
Diagnosis
Sessile feeding indivi
s
0
Fig. 1. Symbion americanus sp. nov., habitus of holotype with
three (of five) attached paratypical Prometheus larvae (pl1–3).
Abbreviations: ad ¼ adhesive disc; bc ¼ brood chamber; bf ¼
buccal funnel; ib ¼ internal bud; m1, 2 ¼ male 1, 2; ms ¼
motile stage; se ¼ host seta; st ¼ stalk; to ¼ toe; wr ¼
wrinkle.
8 0
nov. on mouth append
da, Nephropidae). F
funnel, trunk, stalk, an
or attached Prometh
posterior end (Figs. 1