2 Diversity Over 67,000 species worldwide Live in aquatic environments (both ocean and freshwater)Can burrow, creep on bottom of ocean floorSome are sessile/permanently fixed (barnacles)Examples include: crabs, crayfish, lobster, shrimp, water fleas, brine shrimp, barnacle, daphnia, fish louse (parasite), krill, pill bugs (rollie pollies)Called crustaceans
3 Diversity Some are edible (lobster, shrimp, crayfish, crabs) Others are parasites to other ocean-going organismsFill a wide range of ecological roles and have enormous variationFood, bioindicators, etcCalled MandibulatesWhy? Because of the many pairs of sensory, chewing, food-handling appendages
4 Characteristics of Aquatic Mandibulates Most have two body regions:1) AbdomenLong narrowTail regionIncludes the telson and uropod
5 Characteristics of Aquatic Mandibulates Most have two body regions:2) Cephalothoraxfused head and thorax—chest region,appendages attached to thissegmentcovered by a carapaceDef: a cuticle composed of chitin, protein and calcareous materialUsed for protection but is very flexibleCarapace covers most of the cephalothorax
7 Characteristics of Aquatic Mandibulates AppendagesAll appendages are biramous (two main branches)First two pair:Antennae (2 pair – this distinguishes them from all other arthropods)Next pair:Jaw-like mandiblesUsed to chew and crush foodMaxillaeUsed to hold food
8 Characteristics of Aquatic Mandibulates Appendages, cont.Three pairs of jaw feet called maxillipedsUsed to touch, taste and handle foodClaws for catching foodOne pair of walking legs for each segment (four pairs total)Swimmerets on the abdomenUsed for swimming and to catch sperm
10 Characteristics of Aquatic Mandibulates RespirationGills (if present)Some use diffusion for respirationSegmentsMost have segments (some have more)Nervous SystemNerve cord on ventral side that swells to gangliaDigestive systemDigestive gland mixes food with digestive enzymeStomach, intestines, anus
11 Characteristics of Aquatic Mandibulates Excretory systemGreen gland—regulates amount of salt in bodyReproductionGonopores—pores that release reproductive cellsThe position of these varies according to sexLocation: at the base of a pair of swimmerets or on segments without legs
19 Crayfish Characteristics General Characteristicsfreshwater aquatic invertebratetypically 6 to 8 cm in length, may be as long as 12 cmjointed exoskeletonbody consists ofcephalothorax andabdomen
20 Crayfish Characteristics General Characteristics, cont.paired, jointed appendageshead has 2 pairs of antennae, 1 pair of mandibles, and 2 pairs of maxillaeundergoes ecdysis (shedding of the exoskeleton to accomplish an increase in body size)
21 Crayfish Characteristics Digestive SystemThe digestive tract consists of:1) the foregut,includes an enlarged stomach (grinding)2) the midgut3) the hindgut (functions in water and salt) regulation.4) anus5) digestive glandsecretes digestive enzymes and aids in the absorption of the products of digestion.
23 Crayfish Characteristics Excretory SystemExcretory organs are called the antennal glandsThey excrete the waste products of blood filtration;Ammonia is the primary waste product.Ammonia is also excreted across the gill surfaces and by diffusion across thin parts of the exoskeleton.
25 Crayfish Characteristics Respiratory SystemUse gillsThe gills are located in between the carapace (the exoskeleton of the cephalothorax) and the body wall.Circulatory SystemThe circulatory system of the crayfish is centered around a muscular heart
27 Crayfish Characteristics Nervous SystemThe crayfish nervous system is composed of a ventral nerve cordConcentrated ganglia (anterior end)Giant neurons in the ventral nerve cord function in escape responses.
29 Crayfish Characteristics Endocrine SystemThe endocrine glandsRelease hormones into the bloodThe hormones control functions, such as ecdysis, sex determination, color change and regulation of heart rate
30 Crayfish Characteristics Sensory StructuresChemoreceptorsTactile receptorsfunction in equilibrium, balance, and position sensesStatocystsfunctions in movement and orientationOcelli (simple eye)allows larvae to go toward or away from lightdoes not form imagesCompound eyesmounted on moveable eyestalkslens system made of 14,000 individual receptors
31 Crayfish Characteristics Sexual Characteristics and ReproductionCrayfish have separate sexes.Mating occurs just after the female has molted (usually in the spring).Once they leave their mother, they begin an adult life and reach maturity in anywhere from a few months to a year.The average life span for a crayfish is two to three years.
32 Crayfish Internal Dissection Another dissection
33 Crayfish Characteristics Predator / Prey RelationshipsFeed on living animals and plants,Also consume a fair amount of dead plants, dead or dying animals, and detritus.Crayfish are omnivores.Crayfish do not prey on larger animals, such as fish
34 Terrestrial Mandibulates: Spiders and Insects Phylum Arthropoda
35 Characteristics Segmented bodies Jointed appendages Exoskeleton Specialized for eating, sensing, reproduction, defense and movementExoskeletonHard covering on the outside of the animalLimits the growth of the organism (must shed)Muscles are attached to this layerSecreted by underlying epidermisShed (molted) at intervals
36 Characteristics Bilateral symmetry Muscular system Body cavity Complex Contains two types of musclesBody cavityCoelom is smaller in size Most of body cavity consists of hemocoel (sinuses, or spaces, in the tissues)Filled with blood
37 Characteristics Digestion Circulatory System Complete digestive system Esophagus, crop, gizzard, midgut, hindgut and anusMouthparts modified from appendages and adapted for different methods of feedingCirculatory SystemOpen systemDorsal contractile heart, arteries
38 Characteristics Respiration Obtain oxygen through: 1) body surface (diffusion),2) gills,3) tracheal (air tubes) – carry oxygen to muscles4) book lungsSpiracles—small openings in the exoskeleton through which air opens
39 Characteristics Water retention—3 structures 1) Malpighian tubules— excretory structures that remove metabolic wastes from blood and return water to the cells2) Exoskeleton—prevents water evaporation3) Book Lungs—gas exchange without water loss (also used in respiration)
40 Characteristics Excretory system Paired excretory glands in some Same as the nephridial system of annelids Some with other excretory organs, called Malpighian tubules
41 Characteristics Nervous system Contains same system of annelid (with dorsal brain connected by a double nerve chain)Fusion of ganglia in some species Well-developed sensory organsCompounds eyes with many lenses (can see motion and color)
42 Characteristics Reproduction Sexes usually separate, Paired reproductive organs and ducts; Usually internal fertilization;often go through metamorphosis (change in body form larva to adult)
43 Classification Phylum Arthropoda (most diverse phylum) Subgroups of Terrestrial Arthropods:Subphylum Chelicerata –Characteristics of all:six pairs of appendages that includea pair of chelicerae,a pair of pedipalps, and4 pairs of walking legsNo mandibles and no antennae. Suck up liquid food from their prey.Two body segments (abdomen and cephalothorax)
44 Classification Class Merostomata – Horseshoe crabs are practically unchangedHave an unsegmented, horseshoe-shaped carapace, and a broad abdomen, which has a long spine like telson.Book gills are exposed. They feed at night on worms and small mollusks and are harmless to humans.Include horseshoe crabs
45 Classification Class Arachnida – over 50,000 species Body organization: cephalothorax, abdomenExamples: Spiders (35,000 species), scorpions, ticks, mites
46 Classification Spiders: Scorpions: Mites and Ticks: hunt using strong legs and good eyes; weave silk for web (hunt and reproduction); fangs are modified chelicerae (liquefy prey with venom)Scorpions:long, segmented abdomen with a stinger;Mites and Ticks:mites have one body segment, eat bacteria or skin cells of humans; ticks are mostly parasitic, require blood before molting and can cause Rocky Mtn spotted fever
47 Classification Subphylum Uniramia – Characteristics: Appendages are unbranched. Includes the insects and the myriapods (centipedes and millipedes).Heads resemble the crustacean head but have only one pair of antennae, instead of two.Also have a tympanic membrane for sound Have mandibles and two pairs of maxillaeRespiration is by body surface and tracheal systems,Although juveniles, if aquatic, may have gills.
48 Classification Class Chilopoda - They are active predators with a preference for moist places such as under logs or stones, where they feed on earthworms, insects, etc. Each segment (they have between 10 and 70), except the one behind the head and the last two, bears one pair of appendages.Include: centipedes
49 Classification Class Diplopoda – Include Millipedes Have cylindrical bodies made up of 25 to 100 segments.Abdominal segments each have two pairs.Millipedes are less active than centipedesGenerally herbivorous, living on decayed plant and animal matter
50 Classification Class Insecta – Most numerous and diverse of all arthropods.(There are more species of insects than species in all the other classes of animals combined!!)Have three pairs of legsUsually have two pairs of wings (although some have one pair of wings, or none) Body organization: head, thorax, and abdomen.The head usually bears a pair of large compound eyes, a pair of antennae, and usually three ocelli.