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Subphylum Crustacea: Aquatic Mandibulates. Diversity  Over 67,000 species worldwide Live in aquatic environments (both ocean and freshwater) Can burrow,

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Presentation on theme: "Subphylum Crustacea: Aquatic Mandibulates. Diversity  Over 67,000 species worldwide Live in aquatic environments (both ocean and freshwater) Can burrow,"— Presentation transcript:

1 Subphylum Crustacea: Aquatic Mandibulates

2 Diversity  Over 67,000 species worldwide Live in aquatic environments (both ocean and freshwater) Can burrow, creep on bottom of ocean floor Some 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 organisms  Fill a wide range of ecological roles and have enormous variation Food, bioindicators, etc  Called Mandibulates Why? Because of the many pairs of sensory, chewing, food-handling appendages

4 Characteristics of Aquatic Mandibulates Most have two body regions : ○ 1) Abdomen Long narrow Tail region Includes the telson and uropod

5 Most have two body regions: ○ 2) Cephalothorax fused head and thorax—chest region, appendages attached to this segment covered by a carapace - Def: a cuticle composed of chitin, protein and calcareous material - Used for protection but is very flexible - Carapace covers most of the cephalothorax Characteristics of Aquatic Mandibulates


7 Appendages ○ All appendages are biramous (two main branches) ○ First two pair: Antennae (2 pair – this distinguishes them from all other arthropods) ○ Next pair: Jaw-like mandibles Used to chew and crush food ○ Next pair: Maxillae Used to hold food Characteristics of Aquatic Mandibulates

8 Appendages, cont. ○ Three pairs of jaw feet called maxillipeds Used to touch, taste and handle food ○ Claws for catching food ○ One pair of walking legs for each segment (four pairs total) ○ Swimmerets on the abdomen Used for swimming and to catch sperm Characteristics of Aquatic Mandibulates


10 Respiration ○ Gills (if present) ○ Some use diffusion for respiration Segments ○ Most have segments (some have more) Nervous System ○ Nerve cord on ventral side that swells to ganglia Digestive system ○ Digestive gland mixes food with digestive enzyme ○ Stomach, intestines, anus Characteristics of Aquatic Mandibulates

11 Excretory system ○ Green gland—regulates amount of salt in body Reproduction ○ Gonopores—pores that release reproductive cells The position of these varies according to sex Location: at the base of a pair of swimmerets or on segments without legs

12 Classification  Subphylum Crustacea Class Remipedia Class Cephalocarida Class Branchiopoda ○ Orders: Anostraca (Fairy Shrimp, Brine Shrimp), Notostraca (tadpole shrimp), Diplostraca (water fleas, clam shrimp) Fairy shrimp Brine shrimp Tadpole shrimp Water flea

13 Classification  Subphylum Crustacea, cont. Class Ostracoda Class Maxillopoda ○ Subclasses: Copepoda, Tantulocarida, Branchiura (fish lice), Cerripedia (barnacles) Class Malocostraca ○ Orders: Isopoda (pill bug), Amphipoda, Euphasiacea (krill), Decapoda (shrimps, crabs, lobsters) Fish lice Copepods

14 Classification  Decapods (Order Decapoda) Crayfish, lobsters, shrimp, crabs 10 walking legs Carnivores Eyes on stalks first three pairs of appendages modified for eating

15  Isopods (Order Isopoda) Pill bugs, sow bugs Feed on dead, decaying matter Obtain oxygen from air/moist soil no carapace eyes are not stalked gills on appendages Classification

16  Cerripeds (Subclass Cerripedia) Barnacles Shelled, sessile No eyes, gills, heart or blood vessels Classification Giant Barnacles

17 Copepods ○ Smallest in size ○ Plankton, Krill ○ Feed on algae ○ No gills or abdominal appendages Classification

18 Crayfish External Dissection

19 Crayfish Characteristics General Characteristics ○ freshwater aquatic invertebrate ○ typically 6 to 8 cm in length, may be as long as 12 cm ○ jointed exoskeleton ○ body consists of cephalothorax and abdomen

20 Crayfish Characteristics General Characteristics, cont. ○ paired, jointed appendages ○ head has 2 pairs of antennae, 1 pair of mandibles, and 2 pairs of maxillae ○ undergoes ecdysis (shedding of the exoskeleton to accomplish an increase in body size)

21 Digestive System ○ The digestive tract consists of: 1) the foregut, - includes an enlarged stomach (grinding) 2) the midgut 3) the hindgut (functions in water and salt) regulation. 4) anus 5) digestive gland - secretes digestive enzymes and aids in the absorption of the products of digestion. Crayfish Characteristics


23 Excretory System ○ Excretory organs are called the antennal glands ○ They 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. Crayfish Characteristics


25 Respiratory System ○ Use gills The gills are located in between the carapace (the exoskeleton of the cephalothorax) and the body wall. Circulatory System ○ The circulatory system of the crayfish is centered around a muscular heart Crayfish Characteristics


27 Nervous System ○ The crayfish nervous system is composed of a ventral nerve cord ○ Concentrated ganglia (anterior end) ○ Giant neurons in the ventral nerve cord function in escape responses. Crayfish Characteristics


29 Endocrine System ○ The endocrine glands Release hormones into the blood ○ The hormones control functions, such as ecdysis, sex determination, color change and regulation of heart rate Crayfish Characteristics

30 Sensory Structures ○ Chemoreceptors ○ Tactile receptors function in equilibrium, balance, and position senses ○ Statocysts functions in movement and orientation ○ Ocelli (simple eye) allows larvae to go toward or away from light does not form images ○ Compound eyes mounted on moveable eyestalks lens system made of 14,000 individual receptors Crayfish Characteristics

31 Sexual Characteristics and Reproduction ○ Crayfish 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. Crayfish Characteristics

32 Crayfish Internal Dissection Another dissection

33 Predator / Prey Relationships ○ Feed 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 Crayfish Characteristics

34 Terrestrial Mandibulates: Spiders and Insects

35 Characteristics Segmented bodies Jointed appendages ○ Specialized for eating, sensing, reproduction, defense and movement Exoskeleton ○ Hard covering on the outside of the animal ○ Limits the growth of the organism (must shed) ○ Muscles are attached to this layer ○ Secreted by underlying epidermis ○ Shed (molted) at intervals

36 Bilateral symmetry Muscular system ○ Complex ○ Contains two types of muscles Body cavity ○ Coelom is smaller in size ○ Most of body cavity consists of hemocoel (sinuses, or spaces, in the tissues) ○ Filled with blood Characteristics

37 Digestion ○ Complete digestive system Esophagus, crop, gizzard, midgut, hindgut and anus ○ Mouthparts modified from appendages and adapted for different methods of feeding Circulatory System ○ Open system ○ Dorsal contractile heart, arteries Characteristics

38 Respiration ○ Obtain oxygen through: 1) body surface (diffusion), 2) gills, 3) tracheal (air tubes) – carry oxygen to muscles 4) book lungs ○ Spiracles—small openings in the exoskeleton through which air opens Characteristics

39 Water retention—3 structures ○ 1) Malpighian tubules— excretory structures that remove metabolic wastes from blood and return water to the cells ○ 2) Exoskeleton— prevents water evaporation ○ 3) Book Lungs— gas exchange without water loss (also used in respiration) Characteristics

40 Excretory system ○ Paired excretory glands in some ○ Same as the nephridial system of annelids ○ Some with other excretory organs, called Malpighian tubules Characteristics

41 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 organs Compounds eyes with many lenses (can see motion and color) Characteristics

42 Reproduction ○ Sexes usually separate, ○ Paired reproductive organs and ducts; ○ Usually internal fertilization; ○ often go through metamorphosis (change in body form  larva to adult) Characteristics

43 Classification  Phylum Arthropoda (most diverse phylum) Subgroups of Terrestrial Arthropods: ○ Subphylum Chelicerata – Characteristics of all: - six pairs of appendages that include - a pair of chelicerae, - a pair of pedipalps, and - 4 pairs of walking legs - No mandibles and no antennae. - Suck up liquid food from their prey. - Two body segments (abdomen and cephalothorax)

44 Class Merostomata – ○ Horseshoe crabs are practically unchanged ○ Have 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.mollusks ○ Include horseshoe crabs Classification

45 Class Arachnida – ○ over 50,000 species ○ Body organization: cephalothorax, abdomen ○ Examples: Spiders (35,000 species), scorpions, ticks, mites Classification

46 Spiders: - 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 Classification

47 ○ 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 maxillae - Respiration is by body surface and tracheal systems, - Although juveniles, if aquatic, may have gills. Classification

48 ○ 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 Classification

49 ○ 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 centipedes Generally herbivorous, living on decayed plant and animal matter Classification

50 ○ 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 legs Usually 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. Classification

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