benthic invertebrates, nekton Flashcards
some Cetacea, Pinnipeds & Sirenia
1
Q
state roles of benthic invertebrates in ecosystem functioning
A
- 2° production
- nutrient recycling
- habitat structure
- grazing
- predation
2
Q
the taxonomic group ‘Phylum Cnidaria’
A
2 body forms:
- medusae (jellyfish like)
- polypoid (anemone like)
^have radial symmetry & are diploblastic
3
Q
diploblastic animals
A
have body derived from only 2 embryonic cell layers:
- ectoderm
- endoderm
… but no mesoderm
4
Q
state and describe cnidarians key feature
A
nematocysts
- large organelles produced from Golgi apparatus
- … as secretory product within a specialized cell (nematocyte / cnidocyte)
- nematocysts: used for prey capture and defense and locomotion
5
Q
cold water corals: Lophelia pertusa
A
- these reefs provide habitat for variety of species and living and dead coral skeletons provide biodiversity hot spot on edge of continental shelf
- lives between 80-3000m deep
- found in west scotland and ireland
- damaged by fishing and v delicate & grows slowly => long time for them to recover
6
Q
sea pens: Anthozoa
A
each sea pen is a colony of polyps (cnidarians with polypoid shape)
7
Q
marine invertebrates
A
- porifera -> sponges
- cnidaria -> jellyfish, anemones, corals
- ctenopora -> comb jellies
- polychaeta -> bristle worms (annelida)
- mollusca -> polyplacophora, bivalves, gastropods
- echinodermata -> starfish, brittle stars, sea urchins, sea cucumbers
- crustacea -> decapods, seed shrimp, krill, isopods, barnacles, copepods
- hemichordata -> balanoglossus, saccoglossus
8
Q
hemichordata
A
2 body plans:
- large, solitary acorn worms -> class Enteropneusta
- filter-feeding colonies of the class Pterobranchia.
9
Q
nutrient recycling
A
- way in which elements are continuously being broken down and/or exchanged…
- … for reuse between the living and non-living components of an ecosystem
10
Q
grazing
A
method of feeding
where herbivore feeds on low-growing plants such as grasses or other multicellular organisms (eg. algae)
11
Q
nekton
A
organisms that can move independently of currents
12
Q
importance of nekton
A
- nektonic fish of critical importance to world food supply
- large nekton can profoundly influence marine communities
- important in harvests (current and historical)
13
Q
epipelagic countershading
A
- most epipelagic organisms have ‘countershading’
- they’re bicoloured: dark on top, silvery on bottom
- allows organisms to blend into darker water below and lighted surface above when other organisms look down or up at it
eg. tuna
14
Q
holoepipelagic organisms
A
- spend entire lives in epipelagic zone
- often lay eggs and have epipelagic larval life
- eg. shark, tuna, ocean sunfish
15
Q
meroepipelagic zones
A
- spend part of lives in epipelagic zone
- visit this region to find prey
- spawn in inshore / freshwater regions
- eg. herring, salmon
16
Q
photophores
A
- organs used by fish and invert. to produce light by chemical reaction / through bioluminescence
- most fish that use photophores live in deep sea where light is limited
17
Q
morphological features of nekton in mesopelagic zone
A
- rarely exceeds 10cm long
- good teeth and large mouth
- large, light sensitive, black eyes
- has photophores
18
Q
morphological features of nekton in abyssopelagic zone
A
- “species-specific pattern of photophores”
- small flabby, soft, **nearly transparent flesh **supported by weak bones
- oversized mouth
19
Q
cephalopods
A
- 2 sub-classes: Nautiloidea & Coleoidea
- coleoidea…
-> superorder: Decapodiformes (squid & cuttlefish)
-> superorder: Octopodiformes (octopus & vampire squid) - semelparous -> breeding only once in a lifetime (squid, cuttlefishes & octopuses)
- iteroparous -> multiple reproductive cycles over lifetime (nautiluses)
20
Q
chondrichthyes
fish
A
skeletons that are mainly made of cartilage
2 sub-classes:
-
elasmobranchii (sharks, rays, skates, and
sawfish) - holocephali (chimaeras)
21
Q
osteichthyes
fish
A
“bony fish” -> skeletons mainly made of bone tissue
2 sub-classes:
-
sarcopterygii (lobe-finned fish)
eg. coelacanths & lung fish -
actinopterygii (ray-finned fish)
eg. goldfish & ocean sunfish
22
Q
pinnipeds
A
seals
23
Q
cetaceans
A
includes whales, dolphins & porpoises
24
Q
cetaceans key characteristics
A
- fully aquatic lifestyle
- streamlined body shape
- often large size
- exclusively carnivorous diet
25
sirenia and their characteristics
| sirenia is an **order**
**sea cows**
- fully aquatic, herbivorous mammals
- inhabit swamps, rivers, estuaries, marine wetlands & coastal marine waters
2 distinct families:
- **Dugongidae** -> **1 sp: dugong**
-> SE Asia, Australia & East Africa
- **Trichechidae** -> inc all *manatees*
-> **3 sp**
-> Amazon, West Indian &West African
26
compare and contrast dugong and manatees
dugong:
- short flippers
- whale-like tail (fluke)
- fusiform body
manatee:
- long & flexible flippers
- spatulate tail (fluke)
- rough skin + **algae**
- barrel shaped
27
cold-blooded vs. warm-blooded fish
cold blooded = **poikilothermic** (**most fish** are):
- bodies same temp as env
- not fast swimmers
warm blooded = **homeothermic**:
- found in **warmer** env
- helps them capture prey
28
adaptations of **deep-water** nekton
| like in finding nemo
- mainly fish that **consume detritus / each other**
- lack of abundant food
- **bioluminescence** – photophores
- large, sensitive eyes
- large sharp teeth
- **expandable bodies**
- hinged jaws
- counterillumination
29
counterillumination
- **active camouflage** seen in marine animals eg. firefly squid & midshipman fish
- producing light to **match their backgrounds** in both **brightness & wavelength**
30
what are the predictable env for nekton
| LIFE HISTORY - how they live
- iteroparous -> producing offspring **more than once** during its lifetime
- long-lived **(longevity)**
- delayed maturity
- low-reproductive rates
- migratory
31
life history
series of changes undergone by organism during its lifetime
32
examples of nekton's longevity
- *Osteichthyes:*
e.g. **orange roughy** -> ~150 yrs
- *Chondrichthyes:*
(oldest known vertebrate): **greenland shark** -> ~400 yrs
-> based on radio-carbon dating eye lenses
33
marine **reptiles**
- ectothermic (cold-blooded)
- covered with scales
- breathe **air** with lungs
- have **specialised salt glands** -> **excrete excess salt** taken in from seawater
34
marine **mammals**
- land-dwelling ancestors
- **warm-blooded**
- breathe **air**
- hair/fur
- have kids young
- mammary glands for milk
35
major marine mammal orders
- Carnivora -> pinnipeds, sea otters, polar bears
- Sirenia -> manatee, dugong
- Cetacea -> whales
36
order Carnivora
- prominent canine teeth
what it includes:
- sea otters
- polar bears
- pinnipeds
– Walruses – Seals
– Sea lions – Fur seals
37
seals vs. sea lions & fur seals
- seals lack prominent **ear flaps**
- seals: **smaller front flippers**
- seals: fore flipper claws
- diff hip structures
- diff locomotion strategies
38
order Sirenia
- herbivores
what it includes:
- manatees
– coastal areas of tropical Atlantic Ocean
- dugongs
– coastal areas of Indian and w. Pacific Oceans
39
order Cetacea
Whales, dolphins, porpoises
- elongated skull
- **blowholes** on top of skull
- few hairs
- fluke – **horizontal tail fin for propulsion**
40
Cetacea adaptations
- adaptations to ↑ swimming speed
- adaptations for **deep diving**
- use oxygen efficiently
- muscles **insensitive to buildup of CO₂**
- **collapsible lungs**
41
Suborder Odontoceti (toothed)
of order Cetacea
- dolphins, porpoises, killer whale, sperm whale
- **echolocation** to determine distance and direction to objects
-> determine shape, size of objects
42
dolphins vs porpoises
Dolphins:
- larger, more streamlined shape
- longer rostrum (beak)
- falcate dorsal fin (hooked)
- pointy teeth like killer whales (orca)
Porpoises:
- smaller, more stout body shape
- blunt snout
- triangular, smaller dorsal fin
- blunt or flat teeth
43
echolocation
- toothed whales send sound through water
- sound is reflected, returned to animal, and interpreted
- **evolved inner ear structure** may help toothed whales pick up sounds
- ↑ marine **noise pollution** may affect cetacean echolocation
- good vision of marine mammals limited by ocean conditions
- mammals emit clicks of diff pitches
-> **low freq – great distance**
-> **high freq – closer range**
- dolphins can detect schools of fish at more than 100m
44
Suborder **Mysticeti** (moustached whales) of order Cetacea
- baleen whales
- blue, fin, humpback, gray, right whales
- **fibrous plates of baleen sieve prey items**
- vocalized sounds for various purposes
45
gray whale migration
- **22,000 km** annual migration from coastal Arctic Ocean to Baja California & Mexico
- feeding grounds in Arctic (summer) -> near Alaska
- breeding & birthing grounds in tropical eastern Pacific (winter) -> near Mexico
46
Nekton life-histories consequences
- **scale of movement** requires global efforts “conserving a moving target”
- over-exploitation and longevity:
-> **orange roughy collapsed stock**
- **bycatch impacts** e.g. albatross
47
causes of nekton life-histories
FOOD
- selection for large size – takes time to grow
- resources patchy
- travelling long distances is necessary
- may take yrs to **learn how to find food**
- selection will favour **slow turnover rates**
