Exploring Arthropods: Fascinating Invertebrate World

1. Invertebrates Invertebrates are animals that have no backbone. There are many kinds of invertebrates. You have already learned about 6 phyla.

2. Now, let's learn 1 more! 1. Porifera 2. Cnidaria 3. Platyhelminthes, etc. 4. Mollusca 5. Ctenophora 6. Echinodermata

4. Arthropods The largest animal phylum! There are four main kinds of arthropods. 1. Crustaceans 3. Centipedes & Millipedes 2. Spiders & Scorpions Ticks & Mites 4. Insects

5. Arthropods There are more than 1 million species of arthropods on Earth. There are three characteristics that all arthropods have. 2. segmented body 1. exoskeleton 3. jointed appendages

6. All arthropods have an exoskeleton. A hard, outer covering, composed of chitin, secreted by the underlying tissue.

7. Some arthropods grow too big for their exoskeletons. molt. Molting horseshoe crab - YouTube These arthropods will Molting is to leave an exoskeleton and grow a new one. (A.k.a. ecdysis).

8. Behavioral Changes Associated With Molting. • Most hide. • Land crabs need privacy or won't molt. Hormones get fouled. Sensory input from disturbing factors increases secretion of inhibitory hormone from brain and prevents secretion of molting hormone. • Other crabs eat molting crabs. Can't even trust your relatives!

9. pre-molt stage - the crab is getting ready to molt within a few days. molting activity (ecdysis)- can last up to a few hours. post-molt stage the crab is expanding it's shell and avoiding predators intermolt stage - crab is feeding &continues to increase tissue mass underneath the exoskeleton

10. Crustaceans include... Isopods Copepods Amphipods Barnacles DECAPODS Crabs Lobsters Shrimp

11. General Body Plan

12. ALL CRUSTACEANS POSSESS… • Two pairs of antennae. • Head also has a pair of mandibles and 2 pairs of maxillae. • Joints thin and flexible • Skeleton made of chiton and calcareous material

13. Respiratory System • Smaller crustaceans gas exchange occurs across leg cuticle • Larger crustaceans use gills

14. Nauplius The first larval stage of most crustaceans

16. The Barnacle: • Nauplius larvae (first stage) • Cypris larvae (~13 days, does not eat!) 3) Sessile Barnacle!

20. Many small crustaceans and larvae are suspension feeders (dining on phytoplankton)

21. Horseshoe Crabs: “Living Fossils” Why?

22. They are estimated to be at least 300 million years old. The earliest horseshoe crab species were crawling around the Earth's shallow coastal seas for at least 100 million years before the dinosaurs even arrived Since that time, the Earth's land masses have shifted dramatically, thousands of other species have come and gone, but horseshoe crabs have survived and today remain much as they were those millions of years ago.

23. Horseshoe crabs (Limulidae) are currently represented by four species including Limulus polyphemus (1), which is found along the eastern coast of North and Central America, and three Indo-Pacific species, Tachypleus gigas (4), Tachypleus tridentatus (3) and Carcinoscorpius rotundicauda (2).

24. The horseshoe belongs to its ownclass called Merostomata, which means "legs attached to the mouth." Though they are called "crabs," a quick look at their taxonomy shows that they're not. In fact, they are most closely related to trilobites that existed 544 million years ago.

25. Biomedical Importance: Eye Research Much of what we know about the function of our eyes is the result of studies that began over 50 years ago on the large, compound eyes of the horseshoe crab. Its eyes have a relatively simple construction, and the optic nerve is readily accessible. In addition, it is easy to keep Limulus alive in the laboratory, making it an ideal animal for eye research. LAL Research The discovery of perhaps the horseshoe crab's most important role in human medicine was made by Frederick Bang in the early 1950s. Bang discovered that the blood cells (called amoebocytes) of the horseshoe crab contain a clotting agent that attaches to dangerous endotoxins produced by gram-negative bacteria Limulus amoebocyte lysate is used for testing drugs as well as for screening prosthetic devices such as heart valves or hip replacements. LAL is also used to diagnose spinal meningitis and other diseases.

26. Horseshoe Crab Taxonomy Kingdom: Animalia Phylum:Arthropoda — joint-legged animalsSubphylum:Cheilcerata — animals with no jawsClass:Merostomata — mouth surrounded by legsSubclass:Xiphosura — from the Greek Xiphos meaning sword and ura meaning tailOrder: Xiphosurida — sword-tailed animalsFamily:Limulidae — one living member, LimulusGenus:Limulus— from the Latin, meaning somewhat oblique, odd, or askew and referring to the sideways placement of the compound eyesSpecies:polyphemus — from the Greek, meaning eyed giant and referring to the simple eyes on the front of the shell

30. Ceratoserolis is just one of 585 new species of isopod—a type of marine crustacean related to wood lice—found during the Antarctic Benthic Deep-Sea Biodiversity Project This unusually shaped organism, a male Munna, was also snagged during the deep-sea expedition in the waters around Antarctica between 2002 and 2005.

31. A key question for scientists is whether shallow water species colonized the deep ocean or vice versa. The research findings suggest the glacial cycle of advance and retreat of ice led to an intermingling of species that originated in shallow and deep water habitats. Lead author Professor Angelika Brandt from the Zoological Institute and Zoological Museum, University Hamburg says, “The Antarctic deep sea is potentially the cradle of life of the global marine species. Our research results challenge suggestions that the deep sea diversity in the Southern Ocean is poor. We now have a better understanding in the evolution of the marine species and how they can adapt to changes in climate and environments.” Dr Katrin Linse, marine biologist from British Antarctic Survey, says, “What was once thought to be a featureless abyss is in fact a dynamic, variable and biologically rich environment. Finding this extraordinary treasure trove of marine life is our first step to understanding the complex relationships between the deep ocean and distribution of marine life.” Three research expeditions, as part of the ANDEEP

32. Class Remipedia • Recently discovered (1981) and very primitive class of crustaceans. (11 sp.) • Discovered by Jill Yager, then sport diver and high school teacher, now professor at Antioch College • Long trunk of similar segments, each with a pair of biramous appendages

33. Remipede habitat: a sea cave “blue hole” on Andros Island. Seven species are found in the Bahamas.

34. The giant spider crab of Japan dwarfs all other crustaceans, with a record span of eleven feet between outstretched claws. Spider crabs get their name from their likeness to a spider. They have rounded bodies that are covered with stubby projections (tubercles) and long spindly legs. Rarely seen, large adult spider crabs, Macrocheira kaempferi, normally live at depths of as great as 1,200 feet, migrating in spring to shallower waters to mate and lay eggs. Females lay as many as 1.5 million eggs at a time