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 • Xiphosura – Limulus (horseshoe crab). CHOOSE • Arachnida – Chelicerates with 4 pairs of legs (some not used for walking). ONE 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 Panulirus – Spiny lobster Brachyura – True crabs, they have their abdomen completely hidden under the thorax. Can you identify both sexes? How? (Illustrate in your drawings) 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 • 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 CHOOSE in this environment? ONE 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) 83–97 dehydrated in an acetone/ethanol series, transferred to propylene oxide, and subsequently embedded in TAAB 812s. Ultrathin sections were stained with uranyl acetate and lead citrate (Reynolds 1963). Sections were examined and micrographs were obtained with a Phillips MORGAGNI 268 TEM. Taxonomic section -Phylum Cycliophora Funch and Kristensen, 1995 -Class Eucycliophora Funch and Kristensen, 1995 -Order Symbiida Funch and Kristensen, 1995 -Family Symbiidae Funch and Kristensen, 1995 -Genus Symbion Funch and Kristensen, 1995 (Type species: Symbion pandora Funch and Kristensen, 1995) Symbion americanus sp. nov. (Figs. 1, 2) . Etymology The species epithet has been chosen in accordance with that of the host, H. americanus. Its ending matches Make your representation of a cycliophoran you observed: the masculine gender (Funch and Kristensen 1995) of the genus name. Type material Holotype: feeding individual (whole mount, CYC 231 ZMUC) from sample 1 at Birch Harbor, Maine, USA, 441230N, 681020W, 8 April 2002. Paratypes (whole mounts, CYC 232–266 ZMUC and MCZ 61718–61722; TEM sections, grid box no. M02.01.1): all life stages except for free females and free chordoid larvae, found on mouthparts of ten H. americanus collected as sample 1. See also Table 1. Additional material All life cycle stages, collected in the USA. Sample 2: near Domariscotta, Maine, September 1996; Sample 3: observations in Boston on lobsters from Maine, May 2001; Sample 4: Cape Cod Bay near Sandwich, Massachusetts, October 2003; Sample 5: Birch Harbor, Maine (type locality), date unknown; Sample 6: observations in Stockholm, Sweden, on lobsters from Maine, August 2004. See also Table 1. Diagnosis Sessile feeding individuals of Symbion americanus sp. Fig. 1. Symbion americanus sp. nov., habitus of holotype with nov. on mouth appendages of H. americanus (Decapo- three (of five) attached paratypical Prometheus larvae (pl1–3). Abbreviations: ad adhesive disc; bc brood chamber; bf da, Nephropidae). Feeding individual with buccal ¼ ¼ ¼ funnel, trunk, stalk, and adhesive disc (Figs. 1, 2). Free buccal funnel; ib internal bud; m1, 2 male 1, 2; ms motile stage; se ¼ host seta; st stalk;¼ to toe; wr ¼ or attached Prometheus larva with paired toes at wrinkle. ¼ ¼ ¼ ¼ posterior end (Figs. 1, 3D, 7A); attached Prometheus 8 .